2014 Mercedes E550 - P2190 Bank 2 Rich at Idle - Rough Idle when warm

Question

My 2014 E550 is throwing a P2190 code specifically at idle. The car runs great at highway speeds, but once I come to a stop at a light, the RPMs dip and the engine feels like it is stumbling. It only happens on Bank 2, and the long-term fuel trims are sitting around -22% while stopped.

Sam Holloway · Accepted Answer

The issue was indeed the high-pressure fuel pump on the driver side (Bank 2). The internal diaphragm had a micro-tear leaking fuel into the crankcase. I replaced the HPFP with a genuine Bosch unit (Part #0261520216) and changed the oil immediately to remove the gasoline dilution. After resetting the adaptations and driving 50 miles, the fuel trims returned to -2% and the idle is now rock solid.

Tom Patel · Answer

Smoke test the intake manifold. Even though you are rich at idle, an issue with the charcoal canister purge valve (MOT valve) staying open can pull unmetered fuel vapors into the engine, causing the P2190.

Megan Rivera · Answer

Check your high-pressure fuel pump (HPFP) on that bank. If the internal seal fails, it can leak raw gasoline directly into the oiling system via the camshaft drive, which then gets sucked through the PCV system back into the intake, causing a rich condition.

Dave Kowalski · Answer

Have you looked at the oxygen sensors? A lazy upstream O2 sensor on Bank 2 could be reporting a false lean condition, causing the ECU to dump too much fuel, but usually, that triggers a different code. Check the connector pins for oil wicking from the cam sensors.

2014 Mercedes E550 - P2190 Bank 2 Rich at Idle - Rough Idle when warm

Suggest a repair