What P0175 means
P means powertrain (engine and transmission). The 0 marks a generic code defined by SAE, so the same number means the same thing across makes. The third character, 1, places it in the fuel and air metering subsystem; the last two digits identify the specific fault.
Fuel trim is how much the engine computer is correcting its base fuel calculation, using the upstream O2 sensors as feedback. Positive trim means it is adding fuel to correct a lean mixture; negative means it is removing fuel to correct a rich one. These codes set when the correction reaches its limit.
Bank 2 is the side opposite cylinder 1. Inline engines have only bank 1, so a bank 2 code on an inline engine usually indicates a manufacturer-specific use.
What “System Too Rich” means here
The module has removed as much fuel as it is allowed and the upstream O2 sensor still reads rich. Common directions: leaking injectors, excessive fuel pressure, a purge valve stuck open, a contaminated MAF over-reporting, or a fuel-contaminated O2 sensor.
What you may notice
Symptoms depend on the vehicle and on how the module responds to the fault. Any of these can accompany P0175:
- Hesitation or rough idle
- Higher fuel use
- Misfire codes on some engines
- Fuel smell or black smoke when rich
Causes to consider
- Leaking injector Bank 2
- Faulty MAF sensor
Where to start diagnosing P0175
- Read short and long term fuel trims at idle and at 2,500 rpm. Trims that are high at idle but improve with rpm point to a vacuum leak; trims that are high everywhere point to fuel delivery or air metering.
- Check for vacuum and intake leaks, including PCV hoses.
- Check MAF readings and fuel pressure.
- If both banks are affected, look for a shared cause; if only one, look at that bank.
Clear the code only after recording freeze frame data: it shows the engine speed, load and temperature at the moment the fault set, which is often the best clue to reproducing it.
Live data to watch
These standard OBD2 values relate to P0175. Support varies by vehicle; a value your car does not report will simply be missing.
| Value | What to look for |
|---|---|
| Short and long term fuel trim (PIDs 0x06–0x09) | Combined trims well beyond about ±10% deserve investigation. |
| MAF air flow rate (PID 0x10) | Under-reporting causes lean trims. |
| O2 sensor voltage (PIDs 0x14–0x1B) | Confirms what the trims are reacting to. |
Related codes
Codes from the same fuel trim system family. If several are stored together, the shared part — wiring, a common reference voltage, or the component itself — is the place to start.
Further reading
Symptoms that lead to P0175
If you have not scanned the car yet, or P0175 is one of several codes stored, these guides start from what the vehicle is actually doing.
Frequently Asked Questions
What does P0175 mean?
P0175 is the generic SAE J2012 code for "System Too Rich (Bank 2)". In plain terms, it means the engine computer's fuel trim system monitor has reported "System Too Rich (Bank 2)".
Can I keep driving with P0175?
Usually drivable in the short term. A persistently lean engine can misfire and run hot, so do not ignore it.
What should I check first for P0175?
Read short and long term fuel trims at idle and at 2,500 rpm. Trims that are high at idle but improve with rpm point to a vacuum leak; trims that are high everywhere point to fuel delivery or air metering.
Definition source: SAE J2012 / ISO 15031-6 generic DTC definitions. This is the generic meaning that applies across makes; a manufacturer can define a code more narrowly or add its own sub-codes, so confirm against the service information for your vehicle before replacing parts. Written by the OBDAssistant engineering team — see our editorial policy.