P0400 fault code: what it means

P0400: EGR (exhaust gas recirculation) flow is not as expected.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

carbon-clogged EGR valve
blocked EGR passages or cooler
EGR valve stuck
faulty EGR position or pressure sensor

P0400 by make

Suzuki

EGR flow fault.

Usual causes: sticking or blocked EGR valve; EGR valve wiring; blocked EGR passages

Toyota

EGR flow fault on D-4D diesels: EGR flow is less than expected.

Usual causes: soot-clogged EGR valve and passages; sticking EGR valve; vacuum line or wiring fault

What the repair usually costs

CVT valve body replacement (remanufactured, in car)NZ$1,280–NZ$2,420 · A$1,200–A$2,400
EGR valve replacement or cleanNZ$350–NZ$1,710 · A$330–A$1,630

Not sure what P0400 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.