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P0402: Exhaust gas recirculation (EGR) flow excessive

More gas is flowing through the EGR than it should, often because carbon holds the valve open. It causes a rough idle and hesitation.

Code P0402 at a glance
CodeP0402
SystemEngine and transmission
GroupP04xx, Emissions control
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0402 means

The ECU detects exhaust gas entering the intake when the EGR should be closed or nearly closed. Too much recirculated gas smothers combustion, especially at idle and low revs.

Most common causes

  • EGR valve stuck open with carbon
  • Misrouted vacuum hose holding it open (vacuum operated valves)
  • Vacuum solenoid that does not shut off
  • EGR position sensor reading incorrectly
  • Faulty EGR valve

Symptoms

  • Rough idle or engine stalling
  • Hesitation and lack of power at low revs
  • Hard starting
  • Engine warning light on

Can you drive with P0402?

With care You can drive carefully, but the engine may stall when you stop at a junction. Take it to a garage soon.

How to check it

With the engine idling, check EGR position on your reader: it should be closed. If it stays open, or idle improves when the valve is unplugged, tell the garage.

How to read and clear P0402 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0402 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0402 is a generic code, so it means the same on any make, for example on Abarth, Alfa Romeo, Cupra, Jeep, Nissan, Škoda. See what Final OBD does on your car in makes and models.

What does code P0402 mean?

The ECU detects exhaust gas entering the intake when the EGR should be closed or nearly closed. Too much recirculated gas smothers combustion, especially at idle and low revs.

Can you drive with P0402?

You can drive carefully, but the engine may stall when you stop at a junction. Take it to a garage soon.

How do you clear P0402?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0402 comes back.