P0506 fault code: what it means

P0506: Idle speed is lower than the engine computer wants.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

carbon-fouled throttle body
clogged or stuck idle air control valve
restricted PCV or idle air passage

P0506 by make

Honda

Idle speed lower than expected. On Hondas with electronic throttle, carbon in the throttle body is the usual cause; an idle relearn is needed after cleaning.

Usual causes: dirty throttle body; idle relearn not done after battery or throttle work; intake restriction

Subaru

Idle speed is lower than the ECU wants.

Usual causes: dirty throttle body (carbon build-up); vacuum leak; dirty MAF sensor

What the repair usually costs

A/C compressor replace incl. drier and flush (European)NZ$1,560–NZ$3,200 · A$1,490–A$3,050
MAF (mass air flow) sensor replaceNZ$170–NZ$660 · A$160–A$600
Throttle body clean and idle relearnNZ$90–NZ$190 · A$100–A$200
Electronic throttle body replaceNZ$470–NZ$1,290 · A$440–A$1,190

Not sure what P0506 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.