Damaged, chafed, or corroded wiring in the sensor circuit or its connector; Loose or backed-out terminals at the sensor or module connector; Failed diesel intake air flow B position sensor; Water intrusion or contamination in the connector causing intermittent contact; Faulty or improperly seated communication bus splice or junction connector; Low battery voltage or poor grounds disturbing module communication; Internal fault in the control module that monitors the sensor

DTC codes / U06xx · Network communication / U0655

U0655Lost Communication With Diesel Intake Air Flow B Position Sensor

U0655 is a network communication fault indicating that a control module has lost contact with the diesel intake air flow B position sensor over the vehicle's serial data bus. The computer expects regular status messages from that sensor and flags the code when those messages stop arriving within the required time window.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaNetwork communication

Symptoms you may notice

Illumination of the check engine light or a dedicated service warning lamp
Often no symptoms besides the warning light, especially if the sensor signal is only intermittently missing
Reduced engine power or limp-home mode triggered by the missing sensor data
Rough running, hesitation, or poor throttle response under load
Elevated exhaust smoke or abnormal regeneration behaviour on diesel engines
Intermittent stalling or a no-start condition in severe cases

Common causes, most likely first

Damaged, chafed, or corroded wiring in the sensor circuit or its connector
Loose or backed-out terminals at the sensor or module connector
Failed diesel intake air flow B position sensor
Water intrusion or contamination in the connector causing intermittent contact
Faulty or improperly seated communication bus splice or junction connector
Low battery voltage or poor grounds disturbing module communication
Internal fault in the control module that monitors the sensor

How to diagnose and fix it

Verify battery voltage and charging system health, then clear the code and test-drive to confirm it returns
Inspect the sensor connector and harness for corrosion, chafing, or loose pins, and repair as needed
Check the communication bus wiring and splice points for continuity and shorts using a wiring diagram
Measure sensor reference voltage and ground at the connector to confirm the sensor is receiving power
Substitute a known-good sensor or perform a bidirectional communication test to isolate the sensor from the wiring
Repair or replace the faulty section of harness or the sensor itself, then clear codes and verify communication
If all external checks pass, test the control module's communication circuit and replace the module only as a last resort

What the code does not always mean

A U0655 does not automatically condemn the sensor; a loose connector pin or chafed wire often interrupts communication intermittently.
Low battery voltage or a weak ground can cause multiple U-codes at once, so check power and grounds before replacing parts.
The sensor may still function mechanically while its communication chip has failed, so a visual inspection alone is not conclusive.
Water intrusion into the connector after engine washing or heavy rain is a commonly missed cause of intermittent U0655.
A single stored U0655 with no drivability complaint may be a historical fault from a previous low-voltage event rather than an active failure.

Can I keep driving with U0655?

The vehicle is generally safe to drive short distances to a repair shop, but avoid heavy loads, towing, and long trips until the fault is repaired because the engine may enter limp-home mode without warning. If the engine runs rough or loses power, stop driving and arrange a tow.

Tools that help

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