What it means
The control module monitors the EGR cooler coolant pump command and feedback or electrical state. It sets this code when it detects the pump continuing to run after it has been commanded off.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The EGR cooler coolant pump circulates coolant through the EGR cooler when cooling is needed. The control module monitors its command and electrical state, and sets P24AB when the pump continues running after it has been commanded off. A stuck control driver or a pump that cannot stop moving can cause unnecessary circulation and indicate a pump-control fault.
Common causes
Most likely first.
- Driver stage stuck on
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
How to diagnose it
- Record freeze-frame data and compare the scan-tool pump command with available pump status when the code sets.
- With the pump commanded off, check whether it continues to run and whether the control module still shows an active command.
- Inspect the pump connector and wiring for a control wire shorted to supply or a pin bridging adjacent terminals.
- Check the pump and coolant path for debris or mechanical binding using the vehicle's specified procedure.
- If the command is off but the pump remains powered, test the control circuit and module driver according to the manufacturer's procedure.
Common fixes
- Repair a control wire shorted to supply voltage.
- Clean and secure the pump connector or replace damaged terminals.
- Remove debris that is preventing the pump from stopping freely, if the pump design permits service.
- Replace a pump that is mechanically stuck or worn.
- Repair the control module if its driver remains on with a valid off command.
Can I keep driving?
Avoid long or high-load trips until the pump's stuck-on condition is checked, because incorrect coolant circulation can affect EGR cooler temperature and emissions. If the pump runs continuously and the engine develops knocking or overheating, stop driving.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.