P2190: System Too Rich at Idle Bank 2
The P2190 code indicates that the engine control module (ECM) has detected an excessively rich air-fuel mixture (too much fuel, not enough air) at idle on Bank 2 (the side of the engine not containing cylinder #1). This condition is identified by the oxygen sensor (O2) or air-fuel ratio sensor reporting a voltage or current that indicates a rich mixture. The ECM adjusts fuel trim to compensate, but if the deviation exceeds a threshold, the code is set. Common causes include faulty oxygen sensors, vacuum leaks, fuel pressure issues, or a stuck-open fuel injector.
1. Most Common Causes
- Leaking or dripping fuel injector(s) on Bank 2
- Faulty fuel pressure regulator causing excessive fuel pressure
- EVAP purge valve stuck open
- Contaminated or failing MAF sensor (underestimating incoming air)
- Contaminated or drifting Bank 2 oxygen sensor (false rich reading)
- Exhaust leak upstream of Bank 2 oxygen sensor (Venturi effect pulling in outside air)
- Excessive fuel pressure due to faulty fuel pump or blocked return line
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Rough idle or engine misfire
- Poor fuel economy
- Strong fuel smell from exhaust
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect for vacuum leaks using a smoke machine or propane enrichment.
Step 3: Check fuel pressure with a gauge; compare to specs.
Step 4: Monitor oxygen sensor readings with a scan tool; look for slow response or stuck rich.
Step 5: Test MAF sensor output and clean if necessary.
Step 6: Perform a fuel injector balance test on Bank 2.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with this code as it can cause catalytic converter damage, reduced fuel economy, and potential engine damage. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
The cost varies depending on the root cause. Replacing an oxygen sensor costs $100-$200, while a fuel injector replacement can be $150-$400 per injector. Diagnostic fees are typically $50-$150.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.