An EGR valve stuck open with carbon. A failed EGR control solenoid applying vacuum all the time. A faulty EGR position or pressure sensor (DPFE on many older Fords).

Trouble codes › P0402

P0402 Exhaust Gas Recirculation "A" Flow Excessive Detected

Q: What does P0402 mean?

P0402 means the EGR system is flowing too much exhaust, usually a valve stuck partly open, which causes rough idle and stalling. More exhaust is flowing back into the intake than the engine computer commanded, often because the EGR valve is stuck partly open.

Emissions

P0402 means the EGR system is flowing too much exhaust, usually a valve stuck partly open, which causes rough idle and stalling.

More exhaust is flowing back into the intake than the engine computer commanded, often because the EGR valve is stuck partly open.

Can I keep driving? Yes, but get it fixed soon.

The engine may idle rough or stall at stops, which can be dangerous in traffic. Get it fixed soon.

Common causes

An EGR valve stuck open with carbon
A failed EGR control solenoid applying vacuum all the time
A faulty EGR position or pressure sensor (DPFE on many older Fords)

Symptoms

Rough idle or stalling, especially at stops
Hesitation
Check-engine light

What to check first

Remove and inspect the EGR valve for carbon holding it open.
Check that the vacuum control isn't feeding vacuum at idle.
Test the EGR feedback sensor.
Clean or replace the valve.

What does P0402 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0402

No scanner? Most auto parts stores read check-engine codes for free.

Related codes

General guidance for P0402 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.