Fuel and air

P2180 — System Too Rich Off Idle (Bank 2)

Severity: medium Drive with care, to a shop

What P2180 means

The engine control module used the bank 2 oxygen sensor signal and found the mixture is consistently richer than expected above idle, with fuel trim at its limit trying to lean it out. Normally the ECM keeps the mixture near stoichiometric by adjusting injector pulse width. Bank 2 is the side of the engine that does not contain cylinder 1.

Symptoms

  • Check Engine light on
  • Increased fuel consumption
  • Fuel smell or black smoke from the exhaust
  • Rough running or possible misfire
  • Sluggish acceleration
  • P0175 may be stored along with P2180

Possible causes

  1. Leaking or stuck-open injector on bank 2
  2. Faulty mass airflow (MAF) sensor affecting both banks
  3. Faulty or contaminated bank 2 oxygen sensor (HO2S)
  4. High fuel pressure or a bad pressure regulator
  5. Clogged air filter or restricted air intake
  6. Wiring damage: short to ground or poor connections
  7. Rarely, a faulty ECM

How to diagnose

  1. Scan all codes and freeze-frame data, and check for P0175 or MAF codes
  2. Compare short- and long-term fuel trims on both banks; rich on bank 2 only points to a local cause
  3. Inspect the air filter and intake path for restrictions
  4. Check MAF readings and clean or compare against a known good unit
  5. Measure fuel pressure and its leak-down after shutoff
  6. Test bank 2 injectors: resistance, waveform, cylinder balance and leaks
  7. Inspect wiring and connectors for the oxygen sensor and injectors, checking for shorts to ground
  8. Check oxygen sensor response on a live graph and look for exhaust leaks

Common fixes

  • Replace or clean the leaking injector
  • Clean or replace the MAF sensor
  • Replace the bank 2 oxygen sensor
  • Replace the fuel pressure regulator or fix the cause of high pressure
  • Replace the air filter and clear intake restrictions
  • Repair wiring and connectors

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.