P023A
PowertrainCharge Air Cooler Coolant Pump Control Circuit Open
This is usually a fairly contained electrical fault rather than a wallet-emptier, though it depends on whether the pump itself has packed in. The ECU has lost the control signal to the electric pump that pushes coolant through the charge air cooler circuit, which is what keeps the compressed air from your turbo cool before it hits the engine. You'll see this on petrol turbos and some performance diesels that run a liquid-cooled intercooler setup rather than the simpler air-to-air type. Most of the time it's wiring, connector or the pump itself, and you find out which fairly quickly with a multimeter.
ⓘ Information only. This page provides general educational information about fault code P023A. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P023A mean?
P023A is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Charge Air Cooler Coolant Pump Control Circuit Open.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, sometimes with nothing else obvious at low speeds
- • Power tails off under boost, most noticeable when you put your foot down or pull away hard
- • Intake air temperature reading higher than normal on a scan tool
- • A bit thirstier than usual, especially on a long motorway run
- • Knocking or pinking under load as the hotter intake air upsets the timing
- • Performance drops away when towing or hauling up a long hill
Possible causes
Causes commonly associated with P023A, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Failed coolant pump itself. These are small electric pumps and they do wear out or seize, which can read as an open circuit
- 2. Chafed, broken or rubbed-through wiring in the pump control circuit. Heat and vibration near the front of the engine bay take their toll
- 3. Corroded or loose connector at the pump or in the harness, the classic cause of an open-circuit code
- 4. Failed pump relay on cars that use one, worth checking before you condemn the pump
- 5. Internal fault in the pump that the ECU reads as a broken circuit
- 6. ECM fault driving the control output, uncommon and only worth suspecting once everything else checks out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the freeze frame data alongside the code so you know what the engine was doing when it logged. Temperatures and load at the time tell you a lot
- 2. Find the pump (usually near the radiator or low at the front) and unplug the connector. Look hard for green corrosion, melted pins or a connector that's worked loose
- 3. Back-probe the connector and check whether the ECU is sending the control voltage with the ignition on. No signal points upstream to wiring or the ECM
- 4. Feed the pump 12V directly from the battery and see if it runs and moves coolant. A dead pump here is your answer
- 5. Check continuity and resistance through the control wiring back towards the ECM and compare against the workshop figures. An open reading confirms a broken wire or a duff connector
- 6. If the relay is part of the circuit, swap it for a known-good identical one and recheck
Common questions about P023A
Will my car fail its MOT with this stored? +
The code on its own isn't tested at MOT, but the warning light is. If the engine light is lit when the tester looks at the dash, that's a fail on the MIL check regardless of what the underlying fault is. Sort the cause, clear the code, then drive a few cycles to make sure the light stays off before you book it in. If you've a turbo petrol it won't directly hurt the emissions test, but a lit lamp is enough on its own.
What's this likely to cost me to put right? +
If it turns out to be a connector or a length of damaged wire, you're looking at very little, maybe £40 to £120 at an independent including diagnostic time. A replacement coolant pump is the bigger ticket, with the part somewhere around £80 to £250 and labour on top for draining and bleeding, so call it £200 to £450 fitted at a decent independent garage. A main dealer will charge more for the same job, often half as much again on labour. ECM-related repairs are rare here but push it into the high hundreds, so don't let anyone jump straight to that without testing the cheap stuff first.
How do I work out whether it's the pump, the wiring or the connector? +
Start at the connector because it's free to check. Unplug it and look for corrosion or spread pins, and wiggle the loom while watching live data to see if the fault flickers. If the connector's clean, feed the pump 12V straight off the battery: if it runs, the pump is fine and your problem is the wiring or the control side, so trace the harness back towards the ECM for an open circuit. If the pump does nothing on direct power, it's failed and that's your fix. Doing it in that order saves you buying a pump you didn't need.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →