OBD-II Code P1175 — What It Means & How to Fix It

What Does This Error Mean?

P1175 means Air/Fuel Ratio Sensor — Rich Shift — Bank 2, Sensor 1. This is the Toyota and Lexus Bank 2 counterpart to P1130 and P1129. The wideband A/F sensor on Bank 2 (upstream) has detected a consistently rich mixture that has pushed fuel trims toward the maximum rich-correction limit. You may notice black smoke from the exhaust, fuel smell, rough idle, or poor fuel economy from the Bank 2 cylinders.

Affected Models

Toyota and Lexus vehicles with Bank 2 wideband A/F ratio sensors
Common in Toyota Camry V6 (2GR-FE), Sienna, Avalon, and 4Runner V6
Common in Lexus RX 350, ES 350, GS 350, and IS 350
Common in Lexus GX and LX models with V8 engines

Common Causes

Failed wideband A/F sensor on Bank 2 stuck in a rich reading
Leaking fuel injector on a Bank 2 cylinder causing excess fuel delivery
Failed fuel pressure regulator causing over-pressure on the fuel rail
MAF sensor over-reading air mass and causing the PCM to over-fuel Bank 2
Short to ground in the A/F sensor signal circuit causing a falsely rich reading

How to Fix It

Check Bank 2 fuel trims on a scan tool. Negative LTFT values (below -10%) on Bank 2 confirm the PCM is reducing fuel to fight a rich condition.

Compare Bank 1 and Bank 2 fuel trims. A large difference between banks points to a bank-specific issue rather than a global fuel system fault.
Test the A/F sensor on Bank 2 using a scan tool with live data. The sensor output should vary smoothly with throttle changes. A sensor stuck near the rich limit is faulty.

On Toyota V6 engines, Bank 2 is typically the rear bank (firewall side). Confirm which bank is Bank 2 for your specific engine configuration.
Check fuel pressure at the rail. Pressure above spec points to a leaking pressure regulator. Check for fuel in the vacuum line connected to the regulator.

Normal Toyota fuel pressure is typically 44 to 50 PSI at idle with the vacuum line connected.
Inspect Bank 2 spark plugs. A fouled, black, or wet plug on a Bank 2 cylinder confirms excess fuel in that cylinder — look for a leaking injector.

A cylinder contribution test on a scan tool can identify which cylinder is contributing more or less than normal.
Replace the Bank 2 A/F sensor if fuel pressure and injectors test fine. Use a genuine Toyota/Denso sensor only.

After replacement, clear codes and drive through a warm-up cycle. Monitor Bank 2 fuel trims to confirm they return to normal range.

When to Call a Professional

A/F sensor replacement costs $200 to $500 for parts and labor. Fuel injector replacement is $150 to $400 per injector. Fuel pressure regulator replacement is $150 to $400. MAF sensor replacement is $150 to $400. Always confirm with fuel trim data before replacing the sensor.

Frequently Asked Questions

Is P1175 common on Toyota V6 engines?

It is more common on Bank 1 codes (P1130/P1129) because Bank 1 sensors tend to see higher heat on many Toyota V6 configurations. However, P1175 on Bank 2 does occur, especially when a fuel injector is leaking or the sensor has high mileage.

Can P1175 damage the catalytic converter?

Yes — a persistent rich condition sends excess unburned fuel into the Bank 2 catalytic converter. The converter burns the excess fuel internally, causing overheating and eventual substrate damage. A glowing-hot converter under the Bank 2 side of the vehicle is a warning sign.

Does a rich A/F sensor fault cause misfires?

Indirectly — prolonged rich running can foul Bank 2 spark plugs with carbon deposits. Fouled plugs cause misfires (P030X codes) on the affected cylinders. Fix the rich condition first, then replace any fouled plugs.