P2180: System Too Rich Off Idle (Bank 2)

What does P2180 mean?

P2180 closes the series: bank 2's long-term trim must remove too much fuel above idle, so its multiplicative adaptation sits at the rich limit. GM's 2005 2.8 and 3.6 V6 and the 2008 3.6 LLT use a factor below 0.78, GM's 2024 tables below 0.77, both over two trips. VW's 2014 Touareg 3.0 TSI hybrid and 3.6 VR6 set it below -30 % on bank 2. Unlike P2190, which reacts to excess fuel at idle such as purge vapour, this code rises with load, so look at fuel delivered per injection: pressure regulator or high-pressure pump control, injectors leaking or over-delivering on bank 2, or a bank 2 front sensor reading rich. When P2178 is set as well, check the air mass reading and fuel pressure first. No bulletin naming this code was found.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine lamp on after two trips
• Higher fuel consumption

Common causes

• Medium Injector on bank 2 leaking or over-delivering
• Medium Fuel pressure too high or air mass sensor over-reading, usually with P2178
• Low Bank 2 front oxygen sensor reading rich

Likelihood is a general estimate across vehicles; your make and model may differ.