System Too Rich at Idle Bank 2
Diagnostic trouble code P2190 indicates that the engine control module (ECM) has detected an overly rich air-fuel mixture on Bank 2 specifically during idle conditions. This means the engine is receiving too much fuel or not enough air when the throttle is closed, causing the fuel trims to drop below their acceptable negative thresholds.
While the vehicle can usually still be driven, running too rich for an extended period can damage the catalytic converter and foul spark plugs. It should be diagnosed and repaired soon to prevent costly emissions system damage.
Common symptoms
- Illuminated Check Engine Light
- Rough or stumbling engine idle
- Noticeable decrease in fuel economy
- Strong smell of unburned fuel from the exhaust
- Black smoke emitting from the tailpipe on startup or idle
Likely causes
- Leaking or stuck open fuel injector on Bank 2
- Faulty or dirty Mass Airflow (MAF) sensor
- Defective upstream oxygen (O2) sensor or air-fuel ratio sensor on Bank 2
- Stuck open EVAP purge control valve
- Excessively high fuel pressure due to a failing regulator
What to check before replacing parts
Monitor live data for short and long-term fuel trims on Bank 2 at idle.
Look for: Look for negative fuel trim percentages (often exceeding -15% to -20%) at idle that improve or normalize when engine RPM is increased.
Inspect and test the Mass Airflow (MAF) sensor.
Look for: Check for dirt or debris on the sensor wire. Monitor the MAF g/s reading on a scan tool at idle to see if it matches the manufacturer's specification (typically around 1 g/s per liter of engine displacement).
Test the EVAP purge valve for internal leaks.
Look for: Disconnect the purge valve line to the intake manifold and apply vacuum; if it does not hold vacuum, the valve is stuck open and allowing excess fuel vapors into the engine.
Check the Bank 2 Sensor 1 oxygen sensor data.
Look for: Observe the O2 sensor voltage on a scan tool; it should fluctuate rapidly. If it is stuck high (above 0.8V) at idle but responds normally at higher RPMs, it confirms the rich condition.
Perform a fuel pressure and injector leak-down test.
Look for: Connect a fuel pressure gauge and turn the engine off. If the pressure drops rapidly, it indicates a leaking fuel injector on Bank 2 or a failing fuel pressure regulator.
This page explains the generic P2190 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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