P0402 fault code: what it means

P0402: Too much EGR flow; valve likely stuck open. Can cause rough idle, stalling and black smoke.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

EGR valve stuck partly open with carbon
failed EGR valve motor or solenoid
faulty EGR position sensor
leaking vacuum hose on vacuum-type valves

P0402 by make

Ford

EGR flow too high: the EGR valve is letting through more exhaust than asked, giving rough idle, smoke or low power.

Usual causes: EGR valve stuck open; carbon holding the valve open

Land Rover

EGR flow excessive. Too much exhaust gas being recirculated; can come with turbo control codes after an intake leak.

Usual causes: EGR valve stuck open; split inlet pipe near turbo; EGR valve position sensor

Mercedes-Benz

EGR flow too high. On OM642 usually the EGR valve stuck open.

Usual causes: EGR valve stuck open; EGR valve carbon fouling

Mitsubishi

EGR flow too high: valve not closing properly, often from carbon holding it open.

Usual causes: EGR valve stuck partly open with carbon; faulty EGR valve; EGR position sensor fault

Nissan

EGR flow too high: valve stuck open or jamming (YD25).

Usual causes: EGR valve stuck open from carbon; bent EGR valve shaft; EGR valve position fault

What the repair usually costs

Throttle body clean and idle relearnNZ$90–NZ$190 · A$100–A$200
Parking sensor replace, one sensorNZ$130–NZ$520 · A$130–A$510
Diesel injectors, full set (common-rail 4-cylinder)NZ$2,570–NZ$5,430 · A$2,250–A$4,770
Petrol fuel injectors (port injection, set)NZ$430–NZ$1,420 · A$400–A$1,360

Not sure what P0402 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.