U0624 code meaning
Lost Communication With Coolant Pump B
Network system Generic code U06xx codes Check engine light
What U0624 means
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.
U0624 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0624
- Warning lamp
- Reduced heater output or higher component temperatures after shutdown
Common causes of U0624
- Most 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
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Coolant pump bVehicle bus wiring
What each part of U0624 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 24 | The exact fault in that area. |
What to do next
- Note U0624 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 U0624
What does U0624 mean?
U0624 means "Lost Communication With Coolant Pump B". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with U0624?
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 U0624 fail an emissions test?
Yes, it can. U0624 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 U0624 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. This is a job for a workshop.
Will U0624 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.