Summary
P0175 means the engine is running too rich on Bank 2 — too much fuel or not enough measured air. If P0172 (Bank 1 rich) is also present, the cause is shared between both banks. The most common causes are a faulty upstream O2 sensor on Bank 2 (30%), a leaking injector on Bank 2 (25%), and a dirty MAF sensor over-reporting airflow (20%). Check fuel trims on both banks first to determine whether this is a bank-specific or system-wide issue.
Severity: Moderate — catalyst damage accumulates over time
Safe to drive: Yes, short distances
Repair cost: $8–$500 depending on cause
DIY difficulty: Easy to Moderate
What does P0175 mean?
P0175 is the Bank 2 equivalent of P0172. The PCM adjusts fuel injector pulse width to maintain a 14.7:1 air-fuel ratio. When the upstream O2 sensor on Bank 2 reports a rich mixture, the PCM reduces fuel delivery. P0175 sets when the PCM has pulled fuel as far as it can (typically -20% to -25% long-term fuel trim on Bank 2) and the mixture is still rich.
The key diagnostic question: Is P0172 also present?
- Both P0172 and P0175: The cause is in a shared system — MAF sensor, fuel pressure regulator, EVAP purge valve, or ECT sensor.
- Only P0175: The cause is specific to Bank 2 — a bad O2 sensor on that bank, a leaking injector on that bank, or an exhaust leak before the Bank 2 upstream sensor.
Bank 2 is the side of the engine opposite cylinder 1. On inline engines, there is typically only one bank — P0175 mainly applies to V6 and V8 configurations.