OBD-II Network Communication Diagnostic Codes (U0050-U0100)

In general the wiring harnesses itself will never get a short or have a open within the harness unless its been in a fire or had mechanical damage done to the harness. Sometimes the harness may experience wire fatigue breakage when the harness is subjected to being constantly flexed back and forth.

The harness connectors sometimes fail due to mechanical damage or they become faulty because of corrosion and rust within the connector itself causing the contact pins to no longer carry a signal to the other modules.

So start by first inspecting the wiring harness and connectors for obvious damage or the connector just being loose. If the connectors and the harness passes the inspection then maybe you have a faulty computer module. But before even doing that make sure the battery and the charging system are good and supplying the proper voltages to the various modules.

OBD-II Diagnostic Code U0050

(Vehicle Communication Bus C (+) High)

OBD-II code U0050 indicates a malfunction in the HO2S Heater Control Circuit (Bank 2 Sensor 1).

  • HO2S stands for Heated Oxygen Sensor, also known as an air-fuel ratio sensor.
  • Bank 2 Sensor 1, Most vehicles have two exhaust banks (one for each cylinder bank) and each bank has an oxygen sensor (Sensor 1) upstream of the catalytic converter.
  • A U0050 code signifies that the Powertrain Control Module (PCM) isn't detecting the expected operation of the heater circuit for the oxygen sensor in question. This heater element is crucial for the sensor to reach optimal operating temperature quickly, ensuring it delivers accurate readings about the oxygen content in the exhaust.

    Symptoms of a OBD-II Diagnostic Code of U0050:

  • Illuminated check engine light
  • Decreased fuel efficiency
  • Reduced engine performance
  • Potential Causes of a OBD-II Diagnostic Code of U0050:

  • Faulty oxygen sensor (Bank 2 Sensor 1): The heater element within the sensor itself might be malfunctioning.
  • Wiring issues - Damaged, corroded, or disconnected wiring between the oxygen sensor and the PCM could be interrupting the signal.
  • Faulty PCM - In rare cases, the PCM responsible for controlling the heater circuit might be defective.
  • Diagnosing this code effectively typically involves using a scan tool to check for additional trouble codes and live data readings related to the oxygen sensor and heater circuit. Consulting your car's service manual for specific diagnostic procedures is recommended.

    Diagnosing the exact cause of U0069 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    https://obd2.5150.ca/networkcodes.html

    OBD-II Diagnostic Code U0051

    Vehicle Communication Bus C (-) Open

    OBD-II code U0051 indicates a malfunction in the vehicle's fuel pump control circuit. This circuit is responsible for supplying power and regulating the operation of the fuel pump, ensuring it delivers the correct amount of fuel to the engine.

    Here's a breakdown of the code:

  • U0051 - This code falls under the U category of OBD-II codes, signifying a communication network issue.
  • Fuel Pump Control Circuit - This circuit includes the wiring, fuses, relays, and the Powertrain Control Module (PCM) that work together to control the fuel pump.
  • Symptoms of an OBD-II Diagnostic Code of U0051:

  • Illuminated check engine light
  • Engine stalling or hesitation during acceleration
  • Decreased engine performance
  • Difficulty starting the vehicle
  • Potential Causes of a OBD-II Diagnostic Code of U0051:

  • Faulty Fuel Pump - The fuel pump itself might be failing and unable to maintain proper fuel pressure.
  • Wiring Issues - Damaged, corroded, or disconnected wiring within the circuit can disrupt communication between the PCM and the fuel pump.
  • Blown Fuse or Faulty Relay - A blown fuse or a malfunctioning relay in the circuit could prevent power from reaching the fuel pump.
  • Powertrain Control Module (PCM) Issues - In rare cases, the PCM responsible for controlling the fuel pump circuit could be defective.
  • Diagnosing this code effectively requires a scan tool to check for additional trouble codes and live data readings related to the fuel pump and its circuit.

    OBD-II Diagnostic Code U0052

    Vehicle Communication Bus C (-) Low

    The OBD-II diagnostic code U0052 indicates a problem with the vehicle's communication bus C (-). This bus is essentially a network that allows different electronic control modules (ECMs) in your car to talk to each other. The U0052 code refers to a low voltage condition on the communication bus C (-). This could prevent various modules from exchanging information effectively, potentially leading to malfunctions or unexpected behavior in your car.

    Potential causes of the U0052 code:

  • Faulty wiring or connectors - Damaged or loose wires connected to the communication bus can cause voltage issues.
  • ECM malfunction - A problem with one of the ECMs on the bus could be disrupting communication.
  • Battery voltage issues - A low battery voltage can also affect the communication bus.
  • OBD-II Diagnostic Code U0053

    Vehicle Communication Bus C (-) High

    There isn't a universally defined OBD-II code U0053. Just a notice of a voltage issue.

    OBD-II Diagnostic Code U0054

    Vehicle Communication Bus C (-) shorted to Bus C (+)

    Diagnostic trouble code (DTC) U0054 indicates a short circuit between the positive (+) and negative (-) sides of the vehicle communication bus (C).

    The vehicle communication bus is a network that allows different electronic control modules (ECMs) in your car to communicate with each other. These modules control various systems in your car, such as the engine, transmission, and airbags. A short circuit on the communication bus can disrupt communication between these modules, which can lead to a variety of symptoms, including:

  • Illuminated check engine light
  • Engine performance problems - such as stalling or rough idling
  • Transmission problems - such as shifting issues
  • Malfunctioning airbags
  • OBD-II Diagnostic Code U0055

    Vehicle Communication Bus D

    Manufacturer Specific Code - meaning its definition will vary depending on the car make and model.

    OBD-II Diagnostic Code U0056

    Vehicle Communication Bus D Performance

    Diagnostic Code U0056 is often related to a problem with the transmission fluid temperature sensor, which measures the temperature of the transmission fluid. This code may be triggered by a faulty sensor, incorrect wiring, or an issue with the transmission control module (TCM). The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from replacing the faulty sensor to adjusting the TCM settings.

    OBD-II Diagnostic Code U0057

    Vehicle Communication Bus D (+) Open

    Diagnostic Code U0057 typically indicates a problem with the transmission fluid pressure sensor, which monitors the transmission fluid pressure and sends signals to the transmission control module (TCM) to adjust transmission performance. This code may be triggered by a faulty sensor, incorrect wiring, or an issue with the TCM itself. The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from replacing the faulty sensor to updating the TCM software.

    OBD-II Diagnostic Code U0058

    Vehicle Communication Bus D (+) Low

    Diagnostic Code U0058 is typically related to a problem with the transmission fluid temperature sensor, which measures the temperature of the transmission fluid. This code may indicate that the sensor is not functioning properly, sending incorrect data to the transmission control module (TCM), or that the TCM is not recognizing the sensor's signals. The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from cleaning or replacing the sensor to updating the TCM software.

    OBD-II Diagnostic Code U0059

    Vehicle Communication Bus D (+) High

    Diagnostic Code U0059 typically indicates a problem with the transmission fluid temperature sensor electrical circuit, which is responsible for providing the transmission control module (TCM) with accurate temperature readings. This code may be triggered by a faulty sensor, corrosion or damage to the wiring, or a malfunctioning TCM. The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from cleaning or replacing the sensor to repairing or replacing damaged wiring or updating the TCM software.

    OBD-II Diagnostic Code U0060

    Vehicle Communication Bus D (-) Open

    Diagnostic Code U0060 is typically related to a problem with the transmission fluid level sensor, which monitors the transmission fluid level and sends signals to the transmission control module (TCM). This code may indicate that the sensor is malfunctioning, the wiring is damaged or corroded, or the TCM is not recognizing the sensor's signals. The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from cleaning or replacing the sensor to repairing or replacing damaged wiring.

    OBD-II Diagnostic Code U0061

    Vehicle Communication Bus D (-) Low

    Diagnostic Code U0061 typically indicates a problem with the transmission fluid pressure sensor, which monitors the transmission fluid pressure and sends signals to the transmission control module (TCM). This code may indicate that the sensor is malfunctioning, the wiring is damaged or corroded, or the TCM is not recognizing the sensor's signals. The code may cause the check engine light to illuminate and require attention from a mechanic to diagnose and repair the underlying cause, which could range from cleaning or replacing the sensor to repairing or replacing damaged wiring.

    OBD-II Diagnostic Code U0062

    Vehicle Communication Bus D (-) High

    indicates a malfunction with the vehicle communication bus D (-). This bus acts like a network, allowing various car modules to exchange information.The code appears when the voltage on the bus is abnormally high.

    Possible causes for DTC U0062

  • Short circuit
  • Faulty module connected to the bus
  • Wiring issues
  • Diagnosing the exact cause of U0062 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0063

    Vehicle Communication Bus D (-) shorted to Bus D (+)

    The OBD-II diagnostic trouble code U0063 indicates a fault in your vehicle's communication bus system. There's an electrical short circuit between the positive and negative sides of the vehicle communication bus D. This data bus allows various electronic control modules (ECMs) in your car to talk to each other. A short disrupts this communication, potentially causing various problems depending on which modules are affected.

    Symptoms include but are not limited to:

  • Illuminated warning lights
  • Additional trouble codes related to specific modules that can't communicate.
  • Performance issues ranging from a no-start condition to malfunctioning instrument cluster or inoperative climate control system.
  • Possible causes for DTC U0063:

  • Faulty control module
  • Damaged wiring or loose connections within the communication bus
  • Corrosion in the electrical connectors
  • Diagnosing the exact cause of U0063 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0064

    Vehicle Communication Bus E

    Diagnostic Trouble Code (DTC) U0064 is a generic OBD-II code that indicates a communication issue on the vehicle's communication bus.This bus is a network that allows different control modules in your car to share information with each other.

    Symptoms include but are not limited to:

  • Illuminated warning lights
  • Decreased performance
  • Inoperative features, ranging from a no-start condition to malfunctioning instrument cluster or inoperative climate control system.
  • Possible causes for DTC U0064:

  • Faulty wiring or connectors on the communication bus
  • A malfunctioning control module
  • A software glitch
  • Diagnosing the exact cause of U0064 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0065

    indicates a malfunction with Vehicle Communication Bus E (CAN Bus E)

    The CAN (Controller Area Network) bus is a vital part of your car's communication system. It's a network that allows various electronic control modules (ECMs) to share information with each other. These modules control various systems in your vehicle, including the engine, transmission, airbags, and anti-lock brakes. A DTC U0065 means there's an issue with how data is being transmitted across CAN Bus E.

    Symptoms include but are not limited to:

  • Illuminated malfunction indicator lamp (MIL), also known as the check engine light
  • Reduced engine power
  • Inoperative features controlled by the affected modules
  • Possible causes for DTC U0065:

  • Faulty wiring or connectors
  • Damaged electronic control modules
  • Software glitches
  • Diagnosing the exact cause of U0065 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0066

    Vehicle Communication Bus E (+) Open

    Diagnostic Trouble Code (DTC) U0066 refers to a problem with the Vehicle Communication Bus E (+) Open. Similar to U0065, it indicates a malfunction within the CAN (Controller Area Network) bus system in your car.

    The CAN bus is an essential network for various electronic control modules (ECMs) in your vehicle to communicate with each other. These modules manage critical systems like the engine, transmission, airbags, and anti-lock brakes. A DTC U0066 suggests an open circuit on the positive side of CAN Bus E. This means there's an interruption in the electrical flow on that specific CAN bus channel, preventing proper data transmission.

    Symptoms include but are not limited to:

  • Check engine light being on
  • Reduced engine power
  • Malfunctioning features controlled by the affected modules
  • Possible causes for DTC U0066 include:

  • Damaged wiring or connectors on the positive side of CAN Bus E
  • Faulty electronic control modules connected to the bus
  • Software issues within the affected modules
  • Diagnosing the exact cause of U0066 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0067

    Vehicle Communication Bus E (+) Low

    DTC U0067 refers to a problem with the Vehicle Communication Bus E (+) Low. This code, similar to U0065 and U0066, indicates a malfunction within the Controller Area Network (CAN) bus system in your car, specifically with the positive side of CAN Bus E.

    The CAN bus acts as a communication network allowing various electronic control modules (ECMs) in your vehicle to exchange information. These modules manage essential systems like the engine, transmission, airbags, and anti-lock brakes. DTC U0067 indicates that the voltage on the positive side of CAN Bus E is lower than expected. This low voltage disrupts proper data transmission between modules connected to that particular CAN bus channel.

    Symptoms of a OBD-II U0067 problem code include but are not limited to:

  • Illuminated malfunction indicator lamp (MIL), also known as the check engine light
  • Reduced engine power
  • Malfunctioning features controlled by the affected modules (depending on the specific modules impacted by the communication problem)
  • Possible Causes of U0067:

  • Faulty wiring or connectors on the positive side of CAN Bus E
  • Damaged electronic control modules connected to the bus
  • Software issues within the affected modules
  • Diagnosing the exact cause of U0067 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0068

    Vehicle Communication Bus E (+) High

    Diagnostic Trouble Code (DTC) U0068 indicates a malfunction with the Vehicle Communication Bus E (+) High.

    This code is related to the CAN (Controller Area Network) bus system in your car, similar to the previous codes U0065, U0066, and U0067. However, U0068 signifies a different issue on the CAN Bus E.

    The CAN bus is a network for various electronic control modules (ECMs) to communicate. DTC U0068 suggests an abnormally high voltage on the positive side of CAN Bus E. This disrupts the intended data transmission between modules.

    Symptoms of U0068 code include but are not limited to:

  • Illuminated malfunction indicator lamp (MIL), also known as the check engine light
  • Reduced engine power
  • Inoperative features controlled by the affected modules (depending on which modules are impacted by the communication issue)
  • Inoperative features controlled by the affected modules (depending on which modules are impacted by the communication issue)

    Possible Causes of U0068:

  • Faulty wiring or connectors on the positive side of CAN Bus E (causing a short circuit or other electrical issues)
  • Damaged electronic control modules connected to the bus
  • Software glitches within the affected modules
  • Diagnosing the exact cause of U0068 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    OBD-II Diagnostic Code U0069

    Vehicle Communication Bus E (-) Open

    Diagnostic trouble code (DTC) U0069 indicates a vehicle communication bus (CAN bus) error. The CAN bus is a network that allows different electronic control units (ECUs) in your vehicle to communicate with each other. A U0069 code indicates that there is an open circuit on the CAN bus "E" line.

    This could be caused by a number of factors, including:

  • A loose or disconnected wiring connector
  • A damaged wire
  • A faulty ECU
  • Diagnosing the exact cause of U0069 can be tricky and often requires a professional mechanic with specialized tools. However you can try clearing the code and see if it comes back. Sometimes the code might be due to a fluke or some weird circumstances for it to appear. You can clear the code with an OBD-II scanner and see if it returns after driving.

    Diagnostic Code U0070

    Vehicle Communication Bus E (-) Low

    Diagnostic Code U0071

    Vehicle Communication Bus E (-) High

    Diagnostic Code U0072

    Vehicle Communication Bus E (-) shorted to Bus E (+)

    Diagnostic Code U0073

    Control Module Communication Bus A Off

  • Indicates a possible failure with the control module
  • Indicates a possible failure with the CAN bus
  • Diagnostic Code U0074

    Control Module Communication Bus B Off

    Diagnostic Code U0075

    Control Module Communication Bus C Off

    Diagnostic Code U0076

    Control Module Communication Bus D Off

    Diagnostic Code U0077

    Control Module Communication Bus E Off

    Diagnostic Code U0078

    Control Module Communication Bus F Off

    Diagnostic Code U0079

    Control Module Communication Bus G Off

    Diagnostic Code U007A

    Control Module Communication Bus H Off

    Diagnostic Code U007B

    Control Module Communication Bus I Off

    Diagnostic Code U007C

    Control Module Communication Bus J Off

    Diagnostic Code U007D

    Control Module Communication Bus K Off

    Diagnostic Code U007E

    Control Module Communication Bus L Off

    Diagnostic Code U007F

    Control Module Communication Bus M Off

    Diagnostic Code U0080

    Vehicle Communication Bus F

    Diagnostic Code U0081

    Vehicle Communication Bus F Performance

    Diagnostic Code U0082

    Vehicle Communication Bus F + Open

    Diagnostic Code U0083

    Vehicle Communication Bus F + Low

    Diagnostic Code U0084

    Vehicle Communication Bus F + High

    Diagnostic Code U0085

    Vehicle Communication Bus F

    Open

    Diagnostic Code U0086

    Vehicle Communication Bus F

    Low

    Diagnostic Code U0087

    Vehicle Communication Bus F

    High

    Diagnostic Code U0088

    Vehicle Communication Bus F

    Shorted to Bus F +

    Diagnostic Code U0089

    Vehicle Communication Bus G

    Diagnostic Code U008A

    Vehicle Communication Bus G Performance

    Diagnostic Code U008B

    Vehicle Communication Bus G (+) Open

    Diagnostic Code U008C

    Vehicle Communication Bus G (+) Low

    Diagnostic Code U008D

    Vehicle Communication Bus G (+) High

    Diagnostic Code U008E

    Vehicle Communication Bus G (-) Open

    Diagnostic Code U008F

    Vehicle Communication Bus G (-) Low

    Diagnostic Code U0090

    Vehicle Communication Bus G (-) High

    Diagnostic Code U0091

    Vehicle Communication Bus G (-) shorted to Bus G (+)

    Diagnostic Code U0092

    Vehicle Communication Bus H

    Diagnostic Code U0093

    Vehicle Communication Bus H Performance

    Diagnostic Code U0094

    Vehicle Communication Bus H (+) Open

    Diagnostic Code U0095

    Vehicle Communication Bus H (+) Low

    Diagnostic Code U0096

    Vehicle Communication Bus H (+) High

    Diagnostic Code U0097

    Vehicle Communication Bus H (-) Open

    Diagnostic Code U0098

    Vehicle Communication Bus H (-) Low

    Diagnostic Code U0099

    Vehicle Communication Bus H (-) High

    Diagnostic Code U009A

    Vehicle Communication Bus H (-) shorted to Bus H (+)

    Diagnostic Code U009B

    Vehicle Communication Bus I

    Diagnostic Code U009C

    Vehicle Communication Bus I Performance

    Diagnostic Code U009D

    Vehicle Communication Bus J

    Diagnostic Code U009E

    Vehicle Communication Bus J Performance

    Diagnostic Code U0100

    Lost Communication with ECM/PCM "A"

  • Indicates a possible failure with the PCM
  • Indicates a possible failure with control module circuit
  • Indicates a possible failure with the CAN bus
  • Indicates that there could be a dead battery
  • Indicates a possible failure with the TAC module circuit
  • Indicates a possible failure with the TAC module circuit
  • Indicates a possible failure with the CAN bus




  • Network Codes (U)