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DTC codes / U06xx · Network communication / U069F

U069FLost Communication With Exhaust Pressure Sensor C

U069F is a generic network communication code indicating that a control module has lost contact with the exhaust pressure sensor designated as Sensor C. The module monitoring this sensor, typically the powertrain control module (PCM) or a dedicated emissions control module, has stopped receiving valid data over the controller area network (CAN) bus for a calibrated time period, so it sets this code and may substitute a default value or disable certain exhaust-related functions.

SystemNetwork
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaNetwork communication

Symptoms you may notice

  • Illumination of the malfunction indicator lamp (MIL) on the dashboard, often with no other noticeable symptoms.
  • Reduced engine performance or power, particularly during regeneration or load conditions if the sensor is used for exhaust backpressure control.
  • A stored code in the module that monitors the sensor, sometimes accompanied by other communication or emissions codes.
  • In some vehicles, a message on the driver information center indicating a service emissions system or reduced power.
  • Intermittent operation of exhaust-related features such as diesel particulate filter regeneration or variable valve timing strategies that rely on backpressure data.

Common causes, most likely first

  1. A faulty exhaust pressure sensor C that is internally shorted, open, or otherwise unable to communicate on the bus.
  2. Damaged or corroded wiring in the sensor's communication circuit, including the CAN high or CAN low lines, power, or ground.
  3. A loose, corroded, or disconnected electrical connector at the sensor or at the module it communicates with.
  4. A failed or intermittent module that acts as the gateway or primary controller for the sensor network, such as the PCM or body control module (BCM).
  5. Voltage supply issues, such as a blown fuse or poor ground, that prevent the sensor from powering up and communicating.
  6. Software or calibration errors in the module that cause it to incorrectly flag a communication loss, often resolved by a reflash.
  7. Aftermarket accessories or improper wiring repairs that introduce interference or incorrect bus termination.

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related communication codes in all modules to determine if the fault is isolated to sensor C.
  2. Inspect the sensor C connector and wiring for corrosion, loose pins, or chafing, and repair any obvious damage before replacing parts.
  3. Check the sensor's power and ground circuits with a multimeter to confirm the sensor is receiving the correct voltage and has a good ground.
  4. Measure the resistance and voltage on the communication bus lines at the sensor connector to ensure they match the vehicle's specified values and are not shorted or open.
  5. If the wiring and power are good, substitute a known-good sensor of the same part number to see if communication is restored.
  6. Clear the code and perform a road test to confirm the repair, then verify that no other codes return.
  7. If the fault persists after sensor and wiring checks, diagnose the module that monitors the sensor for internal communication faults or software issues, including checking for technical service bulletins (TSBs) and reprogramming if available.

When the sensor is not the real culprit

  • A loose or corroded ground connection at the sensor or the module can cause intermittent communication loss that mimics a failed sensor, so always check grounds before condemning parts.
  • The code can be set by a low battery or charging system issue that causes voltage drops during cranking, leading the module to lose communication with the sensor momentarily.
  • On some vehicles, the exhaust pressure sensor C is part of a shared bus with other sensors, and a fault in one sensor's wiring can disrupt communication for others, so inspect the entire bus for shorts.
  • Aftermarket exhaust components or modifications that alter backpressure can cause the sensor to report out-of-range values, but U069F specifically indicates a communication loss, not a performance fault, so do not replace the sensor for a performance code.
  • A reflash or software update from the manufacturer may be required after replacing the sensor to ensure the module recognizes the new sensor's communication protocol, especially on newer vehicles.

Can I keep driving with U069F?

You can usually continue driving with this code because it is a communication fault and the vehicle may default to a safe operating strategy, but avoid heavy loads or towing until it is repaired. If the engine enters limp mode or you notice significant power loss, have the vehicle inspected promptly to prevent further emissions system damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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