U0624Lost Communication With Coolant Pump B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Some engines carry a second electric coolant pump, for instance one that keeps coolant moving through the turbocharger after shutdown or feeds a separate heater or low-temperature loop. Which pump is B is decided by the manufacturer. No manufacturer documents U0624 publicly; GM uses U0623 and U062F for its LIN pumps instead. The code means that pump B no longer answers on its data link. Bosch's PAD2 and PCE 2.0 pumps illustrate the design: speed set by PWM or LIN and a built-in diagnostic function that reports faults to the controlling unit. CARB asks for an approved monitoring plan when an electric pump rather than a thermostat governs engine coolant temperature. Wiring and connectors come first; P261A to P261D cover the pump's control circuit.
- What you may notice
- Warning lamp
- Reduced heater output or higher component temperatures after shutdown
- Likely causes
- LikelySignal, supply or ground wire to pump B damaged
- PossibleFuse or relay feeding pump B open
- PossiblePump electronics failed, sometimes after overheating or a seized rotor
- 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.