What P0175 means
With closed-loop control the engine module corrects the injected fuel using the oxygen sensor: short-term fuel trim reacts within fractions of a second, long-term trim stores a learned base correction per load and speed range.
How the engine computer detects it
Positive values mean fuel is being added because the mixture was lean, negative values mean fuel is being removed; around ±10 % is normal. P0175 is the bank 2 counterpart of P0172: long-term trim at its lower limit, mixture still rich. GM evaluates it like bank 1 with a passive test before the first purge and an active test with the purge valve closed; Ford at −25 % with purge off. Two trips, no limp mode. P0175 alone points to a bank-specific cause such as a leaking injector on bank 2; together with P0172 to fuel pressure, purge, ethanol learning on flex-fuel vehicles or fuel in the oil. GM and Ford bulletins document wrongly learned ethanol content and a purge valve stuck open as causes.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on (after two drive cycles)
- Higher consumption, fuel smell
- Black smoke, sooted spark plugs
- Rough idle or starting problems after refuelling; converter damage possible later
Common causes
- Purge valve stuck open or charcoal canister saturated Most likely
- Leaking or dripping injectors on bank 2 (also direct injection) Possible
- Fuel pressure too high (faulty regulator, blocked return, regulator vacuum hose) Possible
- Fuel in the engine oil (short trips, leaking injectors), vapour via crankcase ventilation Possible
How to diagnose P0175
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: oxygen sensor bank2 sensor1, mass air flow sensor, fuel system, intake manifold.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 1
- Fuel and air metering
- 75
- Specific fault
Questions drivers ask
Can I drive with code P0175?
Usually yes for a short time, if the car drives normally, the temperature gauge reads normal and the check engine light is steady. If the light flashes, the engine loses power or overheats, or other warning lights come on, pull over and have it checked.
Will my car pass an emissions inspection with P0175?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0175 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0175 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0175. They can point to a shared cause, so it's worth checking them together.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.