P2177 fault code: what it means

P2177: System too lean off idle, bank 1: the mixture goes lean when driving, not at idle.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

dirty or failing MAF sensor
weak fuel pump or blocked filter
intake leak after the MAF
clogged injectors

P2177 by make

Audi

Engine running lean away from idle (bank 1). Usually unmetered air or weak fuel supply. Can cause hesitation and misfires.

Usual causes: intake or crankcase breather (PCV) leak; failing fuel pump; faulty MAF sensor (G70); exhaust leak before the oxygen sensor

Skoda

Engine running lean away from idle (bank 1). Usually unmetered air or weak fuel supply. Can cause hesitation and misfires.

Usual causes: intake or crankcase breather (PCV) leak; failing fuel pump; faulty MAF sensor (G70); exhaust leak before the oxygen sensor

Volkswagen

Engine running lean away from idle (bank 1). Usually unmetered air or weak fuel supply. Can cause hesitation and misfires.

Usual causes: intake or crankcase breather (PCV) leak; failing fuel pump; faulty MAF sensor (G70); exhaust leak before the oxygen sensor

Volvo

Long-term fuel trim at its upper limit: the engine is running lean. Often a crankcase vent (PCV) or intake leak.

Usual causes: blocked or split PCV system; intake leak; weak fuel pump; faulty MAF sensor

What the repair usually costs

Air-fuel ratio / front O2 sensor replace (upstream)NZ$270–NZ$750 · A$260–A$730
O2 sensor replace (downstream / after cat)NZ$180–NZ$480 · A$180–A$460
MAF (mass air flow) sensor replaceNZ$170–NZ$660 · A$160–A$600
PCV valve / oil separator replacementNZ$110–NZ$920 · A$110–A$900

Not sure what P2177 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.