Fuel and air

P2189 — System Too Rich at Idle (Bank 1)

Severity: medium Drive with care, to a shop

What P2189 means

The engine computer watches the air-fuel mixture through the oxygen sensors and adjusts fuel delivery with fuel trims. P2189 sets when, at idle on bank 1, the computer has to cut fuel heavily and the mixture is still too rich. Other operating ranges may stay within normal limits.

Symptoms

  • Rough idle
  • Black exhaust smoke
  • Fuel smell at idle
  • Check Engine light on
  • Possible misfire or hesitation
  • Increased fuel consumption

Possible causes

  1. Leaking fuel injector
  2. EVAP purge valve stuck open
  3. Coolant temperature sensor reading too cold
  4. High fuel pressure or a faulty pressure regulator
  5. Dirty or malfunctioning injectors
  6. Intake leak or faulty MAF reading skewing fuel trims

How to diagnose

  1. Scan for codes and freeze frame data, and review short- and long-term fuel trims at idle
  2. Compare the coolant temperature sensor reading with actual engine temperature
  3. Test the EVAP purge valve: it should stay closed at idle and not leak vacuum
  4. Measure fuel pressure and check that it holds after shutdown
  5. Check injector wiring and cylinder balance, and run an injector leak-down test if needed
  6. Inspect the intake and exhaust for leaks and check MAF and oxygen sensor data
  7. Smell the engine oil for fuel dilution

Common fixes

  • Replace or clean the leaking or sticking injector
  • Replace the EVAP purge valve
  • Replace the coolant temperature sensor
  • Replace the fuel pressure regulator or faulty fuel system part
  • Fix air leaks and replace a faulty MAF or oxygen sensor

Questions and answers

What does P2189 mean?

It means the engine runs too rich at idle on bank 1 and the computer cannot correct it with normal fuel trims. Common culprits are an injector, the purge valve or the coolant temperature sensor.

Can I drive with code P2189?

Briefly, yes, but don't put off the repair. A rich mixture wastes fuel, fouls plugs and can damage the catalytic converter.

Why does P2189 only show up at idle?

At idle, a small extra amount of fuel or purge vapor affects the mixture much more than under load. That is why a leaking injector or open purge valve shows up there first.

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.