Air trapped in the cooling system after recent service or a coolant leak.; Low coolant level due to a leak or improper filling procedure.; Faulty auxiliary coolant pump with worn bearings or internal damage.; Blocked or restricted coolant passages in the pump or hoses.; Damaged wiring or connector to the pump, causing intermittent signals.; Failed pump control module or relay, leading to overspeed detection.; Engine control module software issue or corrupted adaptation values.

DTC codes / P2Dxx · Hybrid propulsion / P2D01

P2D01Motor Electronics Coolant Pump A Overspeed/Air in System

Q: What does code P2D01 mean?

Motor Electronics Coolant Pump A Overspeed/Air in System. This code indicates that the engine control module has detected an overspeed condition or air in the motor electronics coolant pump 'A' circuit, which is typically an electric auxiliary pump used to circulate coolant through the turbocharger or battery pack. The computer compares commanded pump speed with feedback from the pump, and it sets this code when the pump runs faster than expected or when air pockets cause erratic operation.

This code indicates that the engine control module has detected an overspeed condition or air in the motor electronics coolant pump 'A' circuit, which is typically an electric auxiliary pump used to circulate coolant through the turbocharger or battery pack. The computer compares commanded pump speed with feedback from the pump, and it sets this code when the pump runs faster than expected or when air pockets cause erratic operation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms.
Reduced engine performance or limp mode if the pump is critical for turbocharger cooling.
Overheating warning or elevated coolant temperature gauge reading in some cases.
Whining or grinding noises from the auxiliary coolant pump area.
Intermittent operation of the pump, leading to sporadic warning lights.

Common causes, most likely first

Air trapped in the cooling system after recent service or a coolant leak.
Low coolant level due to a leak or improper filling procedure.
Faulty auxiliary coolant pump with worn bearings or internal damage.
Blocked or restricted coolant passages in the pump or hoses.
Damaged wiring or connector to the pump, causing intermittent signals.
Failed pump control module or relay, leading to overspeed detection.
Engine control module software issue or corrupted adaptation values.

How to diagnose and fix it

Check coolant level and inspect for leaks; top up and bleed the system according to the manufacturer's procedure.
Use a scan tool to command the pump on and verify actual speed versus commanded speed, listening for abnormal noises.
Inspect the pump wiring and connector for corrosion, loose pins, or damage; repair as needed.
Perform a coolant system pressure test to confirm no leaks and ensure proper bleeding.
If air is suspected, run the manufacturer's coolant bleed routine to remove trapped air.
Replace the auxiliary coolant pump if it fails functional tests or shows mechanical wear.
Clear the code and road test to confirm the repair, monitoring live data for pump speed and coolant temperature.

Air Pockets Often Mimic Pump Failure

Many technicians replace the auxiliary coolant pump unnecessarily when the real cause is air trapped in the system after a coolant flush or repair.
A weak battery or charging system issue can cause the pump to run erratically and set an overspeed code, so always check system voltage first.
The pump may only act up when the engine is cold or under specific load conditions, so intermittent codes require thorough live data logging.
After replacing the pump, the cooling system must be bled properly; otherwise, the new pump can set the same code immediately.
This code can be set by a faulty coolant temperature sensor giving false readings, leading the module to command incorrect pump speeds.

Can I keep driving with P2D01?

You can usually drive short distances to a repair shop, but avoid heavy loads or sustained high-speed driving because the auxiliary pump may be needed to cool critical components. If the engine temperature gauge rises above normal or a red warning appears, stop safely and shut off the engine.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.