U0641 code meaning
Lost Communication With EVAP System Pressure Sensor/Switch Circuit A
Network system Generic code U06xx codes Check engine light
What U0641 means
Pressure sensor A is the main input for the evaporative leak test that CARB 1968.2 (e)(4) requires: with the system sealed, the controller follows how pressure in tank and canister rises or falls. Newer designs often use a relative pressure sensor with SENT output; Melexis' MLX90821, for example, spans about −0.06 to 0.26 bar in its SENT version and can add a media temperature. U0641 means these digital messages are missing or unusable, which (e)(15.2.1)(B)(i) treats as its own fault; an analog sensor would log P0450 to P0454. Audi's 2.0 TFSI bulletin for 2021–2023 A4/A5 separates sporadic entries, caused by interference and fixed in the harness, from permanent ones that need normal diagnosis. The leak test stays blocked and the MIL is on.
U0641 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0641
- MIL on
- EVAP leak monitor not ready, possible inspection failure
- No noticeable change in driving
Common causes of U0641
- Most likelyElectrical interference or damage on the sensor signal line
- PossibleConnector at the tank or canister sensor loose, wet or corroded
- PossiblePressure sensor A itself no longer sends
- Less likelySensor supply or ground missing
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP pressure sensor aVehicle bus wiring
What each part of U0641 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 41 | The exact fault in that area. |
What to do next
- Note U0641 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0641
What does U0641 mean?
U0641 means "Lost Communication With EVAP System Pressure Sensor/Switch Circuit A". Pressure sensor A is the main input for the evaporative leak test that CARB 1968.2 (e)(4) requires: with the system sealed, the controller follows how pressure in tank and canister rises or falls. It is a generic code, so it means the same on every make.
Is it safe to drive with U0641?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will U0641 fail an emissions test?
Yes, it can. U0641 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0641 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will U0641 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.