U0649Lost Communication With Coolant Pump D
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Coolant pump D is the fourth auxiliary electric pump in the generic lettering that runs from A (U0623) through B and C (U0624, U062F) to E (U0698). What D circulates is up to the manufacturer; GM, for example, assigns C to its low-temperature loop, while Mercedes uses the E code for a pump of its low-temperature circuit. U0649 is set when pump D, controlled over LIN or a similar link, no longer sends a response. No manufacturer documents U0649 publicly. Pumps of this kind receive speed commands over LIN or PWM and report their own diagnosis, as Bosch describes for the PDE. Its circuit and internal faults are P2B66 to P2B6C, with P2C49 and P2BA1 for performance and underspeed. Loss of the pump leaves its loop without circulation.
- What you may notice
- Warning lamp, depending on manufacturer the MIL
- Components on the affected loop run warmer than normal
- Likely causes
- LikelyLIN, supply or ground wire to pump D damaged
- PossibleCorroded pump D connector
- PossiblePump D electronics failed
- RareController acting as LIN master faulty or needing a software update
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.