P0175 System Too Rich (Bank 2)
The rich-running condition of P0172, on the engine's second cylinder bank.
Fuel & air
Bank 2 is the side of a V or flat engine without cylinder 1. As with the lean codes, whether P0172 appears alongside is the key clue: both banks means a shared cause such as fuel pressure, the MAF, or the purge valve; bank 2 alone means an injector or sensor local to that side.
Diagnose P0175 on your specific vehicle Add your year, make and model for ranked causes, repair videos and the exact parts you needCan I keep driving?
Driveable
Short term, but don't let it run for weeks.
How serious
Moderate to high. Cumulative converter and bore-wear damage, same as P0172.
Symptoms you'll notice
- Fuel smell
- Black smoke
- Poor economy
- Rough idle
- Often stored with P0172
What causes P0175
Ordered by what to check first — how likely each cause is, weighed against what it costs to rule out. Working down the list in order is what stops you replacing an expensive part to fix a cheap problem.
Shared cause with bank 1
P0172 and P0175 together point at fuel pressure, the mass airflow sensor, the coolant temperature sensor, or the EVAP purge valve — anything feeding both banks. Do not go hunting for two separate injector faults.
Leaking injector on bank 2
A single seeping injector on that side, usually with a misfire code naming the cylinder.
Failing bank 2 upstream oxygen sensor
Compare its live readings against the bank 1 sensor; a sensor that never crosses or sits pinned is suspect.
High fuel pressure
A failed regulator or restricted return line over-fuels both banks, but can trip one first.
How to diagnose it
- Check whether P0172 is also stored — that single fact splits the diagnosis in two.
- Compare bank 1 and bank 2 fuel trims and oxygen sensor waveforms.
- Test fuel pressure against spec.
- Inspect bank 2 spark plugs for sooty fouling to confirm which cylinders are running rich.
Parts you might need
Tools for the job
- OBD-II scanner with live data
- Fuel pressure gauge
Related trouble codes
- P0172 — System Too Rich (Bank 1)
- P0174 — System Too Lean (Bank 2)
- P0430 — Catalyst System Efficiency Below Threshold (Bank 2)
Fitment matters. Causes and parts above are the common cases for P0175 across vehicles. The specific part numbers, procedures and torque specs vary by year, make, model and engine — always confirm against service data for your vehicle before buying parts or starting work.