P2189
System Too Lean at Idle (Bank 2)
- Severity
- Medium
- Driving
- Drivable — book it in
The mixture on bank 2 is too lean - too much air for the fuel being delivered - and specifically when running at idle, with the throttle closed. The module has run out of adjustment trying to correct it. The condition named in the code is the useful part: At idle the engine draws very little air, so any leak makes a large proportional difference - which is why a vacuum leak shows here before it shows anywhere else.
Possible causes
- CommonVacuum or intake leak
- CommonFaulty or dirty mass airflow sensor under-reporting airflow
- CommonWeak fuel pump, blocked filter or clogged injectors
- CommonExhaust leak before the oxygen sensor, fooling it
- PossibleLow fuel pressure from a failing regulator
- PossibleFailing oxygen sensor reporting lean when the mixture is correct
What you might notice
- Rough or hunting idle
- Hesitation or a flat spot
- Check engine light on
- Slightly reduced fuel economy
- Sometimes no noticeable symptom
What to check, in order
- Look for a vacuum leak first - this is the most common cause by a wide margin.
- Watch fuel trim on the live data screen and note how it changes with engine speed and load. That pattern is worth more than any single reading.
- Inspect the mass airflow sensor element. A dirty sensor under-reads airflow, so the module injects too little fuel.
- Check for exhaust leaks between the engine and the oxygen sensor.
- A persistent lean mixture raises combustion temperatures. Do not ignore this for long, particularly on a turbocharged engine.
Read this code from your own car
Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.
Where this code sits
P00xxP01xxP02xxP03xxP04xxP05xxP06xxP07xxP08xxP09xxP0AxxP0BxxP0CxxP0DxxP0ExxP0FxxP10xxP11xxP12xxP13xxP14xxP15xxP16xxP17xxP18xxP19xxP1AxxP1BxxP1CxxP1DxxP1ExxP1FxxP20xxP21xxP22xxP23xxP24xxP25xxP26xxP27xxP28xxP29xxP2AxxP2BxxP2CxxP2DxxP2ExxP2FxxP30xxP31xxP32xxP33xxP34xxP35xxP36xxP37xxP38xxP39xxP3AxxP3BxxP3CxxP3DxxP3ExxP3Fxx
Fuel and air metering
P2100P2101P2102P2103P2104P2105P2106P2107P2108P2109P2110P2111P2112P2113P2114P2115P2116P2117P2118P2119P2120P2121P2122P2123P2124P2125P2126P2127P2128P2129P2130P2131P2132P2133P2134P2135P2136P2137P2138P2139P2140P2141P2142P2143P2144P2145P2146P2147P2148P2149P2150P2151P2152P2153P2154P2155P2156P2157P2158P2159P2160P2161P2162P2163P2164P2165P2166P2167P2168P2169P2170P2171P2172P2173P2174P2175P2176P2177P2178P2179P2180P2181P2182P2183P2184P2185P2186P2187P2188P2189P2190P2191P2192P2193P2194P2195P2196P2197P2198P2199