Fuel & air metering · Powertrain · generic (SAE-defined)
P0175: System Too Rich (Bank 2)
P0175 means the engine computer has removed as much fuel as it can on bank 2, the side opposite cylinder 1, yet that bank is still running rich.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0175 sets
The powertrain control module (PCM) subtracts fuel from bank 2 when the bank 2 upstream oxygen sensor reports a rich exhaust, pushing fuel trims negative. If the correction remains past its calibrated limit for long enough, the PCM sets P0175. This code applies only to engines with two cylinder banks. Limits vary by manufacturer.
Common causes of P0175
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Leaking fuel injectors on bank 2
- Fuel pressure too high from a faulty regulator
- Mass air flow (MAF) sensor reading higher than actual airflow
- Stuck-open evaporative (EVAP) purge valve
- Coolant temperature sensor falsely reading cold
- Fuel-diluted engine oil venting through the positive crankcase ventilation (PCV) system
P0175 symptoms
- Check engine light on
- Reduced fuel economy
- Fuel odor or black smoke
- Rough idle or misfires
- Possible hard starting when hot
How P0175 is diagnosed
- Scan for codes; P0172 with P0175 suggests a cause shared by both banks.
- Compare bank 1 and bank 2 fuel trims to see whether the problem is isolated to bank 2.
- Test fuel pressure and check for pressure bleed-down after shutdown.
- Check the purge valve for leakage when commanded closed.
- Verify MAF readings and coolant temperature sensor accuracy.
- Pull bank 2 spark plugs and look for heavy carbon or fuel fouling.
Typical fixes for P0175
- Replace leaking bank 2 injectors
- Replace a faulty fuel pressure regulator
- Clean or replace the MAF sensor
- Replace the EVAP purge valve
- Replace the coolant temperature sensor
- Change fuel-contaminated oil and fix the underlying cause
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0175 FAQ
What does code P0175 mean?
P0175 means the engine computer has removed as much fuel as it can on bank 2, the side opposite cylinder 1, yet that bank is still running rich. The standard definition is "System Too Rich (Bank 2)."
Can I drive with a P0175 code?
Short-term driving is usually possible, but running rich raises fuel consumption and can overheat the catalytic converter. Get it diagnosed promptly, and pull over if the check engine light flashes.
Why would only bank 2 run rich?
A leaking injector on that side, or an exhaust or sensor problem specific to bank 2, can make that bank rich while bank 1 remains normal. Shared causes like fuel pressure usually affect both banks.
Can P0175 foul spark plugs?
Yes. Extra fuel leaves soot on the plugs, which can eventually cause misfires on bank 2 cylinders.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.