P02E3: Diesel Intake Air Flow A Control Circuit High
What to do
Mention if the engine shudders or shakes when you switch it off. That is the most recognisable sign of this valve not working, and it is genuinely useful for confirming the diagnosis.
Ask for the connector and wiring to be checked before the valve is replaced. This is an electrical fault code rather than a mechanical one, and the valve sits in a hot part of the engine bay where connectors suffer.
Expect emissions codes alongside it. This valve is what lets exhaust gas recirculation work, so faults there are often consequences of this one rather than separate problems.
Not urgent for safety, but worth doing. The engine will run, though emissions control and particulate filter regeneration will both be compromised.
What this code means
The control circuit for the diesel intake air flow valve is sitting higher than commanded.
A diesel intake throttle is not what a petrol throttle is, and confusing the two sends the diagnosis the wrong way. A diesel controls power by fuel quantity, not by throttling air — so this valve is not there to make the engine go. It does three other jobs:
- It creates intake depression so exhaust gas recirculation can flow, since EGR only moves if intake pressure is below exhaust pressure.
- It closes at shutdown to stop the engine dieseling to a halt on a shudder, which is why it is often called an anti-shudder valve.
- It restricts air during particulate filter regeneration to help raise exhaust temperature.
A circuit reading high means a short to a supply voltage or an open circuit, and the module cannot tell which from the inside. Measuring at the connector with the valve unplugged separates them in minutes.
The symptom people actually notice is the shutdown. A valve that cannot close makes the engine stop with a shake rather than cleanly, and a driver reporting 'it judders when I switch it off' is describing this family precisely.
Carbon is the ordinary enemy here, but note that carbon jams the valve mechanically and sets a performance code — a circuit code is electrical, so check the connector and harness first.
Likely causes
Start here
- Open circuit in control wiring · moderate
- Corroded or loose connector · easy
Less common
- Wiring shorted to voltage · moderate
- Heat damage to wiring insulation · moderate
- Faulty EGR throttle valve · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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