P0175: System Too Rich (Bank 2)
System: Fuel and air mixtureBank 2 of a V engine is running rich and the computer cannot pull out enough fuel to correct it.
Severity: 2 of 4
Usually drivable for a short time with a steady light and smooth running. Get it diagnosed soon to protect the spark plugs and the catalytic converter. Park it if you smell strong raw fuel, see a leak, or the light flashes.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0175 means
P0175 is the bank 2 twin of P0172. Bank 2 is the side of a V6 or V8 that does not contain cylinder number 1. The front oxygen sensor on that side keeps reporting a rich mixture after the computer has trimmed fuel to its limit.
When P0175 shows up alone, look at parts that serve only bank 2, such as a leaking injector on that side or a tired bank 2 front sensor. When it shows up with P0172, look at shared parts first.
Common causes (cheapest likely first)
- Faulty MAF sensor. Affects both banks and often sets P0172 at the same time.
- Purge valve stuck open. Fuel vapor floods the intake, usually showing on both banks.
- Leaking injector on bank 2. A side specific cause. Look for a misfire code on a bank 2 cylinder.
- Coolant temperature sensor reading cold. The engine keeps getting warm up enrichment.
- Worn bank 2 front oxygen or air fuel ratio sensor. Can report a false rich reading on that side only.
Symptoms
- Steady check engine light
- Fuel smell
- Poor fuel economy
- Rough idle
- Possible misfires on bank 2
DIY difficulty: Moderate
Same approach as P0172. Compare bank 1 and bank 2 fuel trims in live data: if only bank 2 is rich, focus on that side.
Tools: OBD-II scanner with fuel trim data, MAF sensor cleaner, Fuel pressure gauge, Multimeter
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| MAF sensor cleaning or replacement | $10 to $250 | 0.2 to 0.5 h | $10 + 0.2 × $110 = $32 $250 + 0.5 × $190 = $345 |
| Purge valve | $25 to $150 | 0.3 to 1.5 h | $25 + 0.3 × $110 = $58 $150 + 1.5 × $190 = $435 |
| Fuel injector, bank 2 | $50 to $250 | 1.0 to 3.5 h | $50 + 1.0 × $110 = $160 $250 + 3.5 × $190 = $915 |
| Bank 2 front oxygen or air fuel ratio sensor | $40 to $250 | 0.3 to 1.2 h | $40 + 0.3 × $110 = $73 $250 + 1.2 × $190 = $478 |
Watch a repair video
Search YouTube for “P0175 fix” videos. Pick a recent video that matches your engine, and confirm the diagnosis before buying parts.
By make
This code works the same way on every make. See brand notes.
Repair manuals
Step-by-step service manuals with torque specs and wiring diagrams:
Haynes manuals Chilton manuals
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Related codes
Check for recalls
Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.
FAQ
Is P0175 serious?
Not an emergency in most cases, but extra fuel damages plugs and the catalytic converter over time. Plan to fix it within days or weeks.
Can I get P0175 on a four cylinder engine?
Generally no. Inline four cylinder engines only have bank 1, so they set P0172 instead.
Should I replace the oxygen sensor first?
Only after checking fuel trims, the MAF sensor, and the purge valve. A sensor that sees a rich mixture is often reporting correctly.