P2197
O2 Sensor Signal Stuck Lean (Bank 2 Sensor 1)
- Severity
- Medium
- Driving
- Drivable — book it in
The upstream oxygen sensor on bank 2 is stuck reporting lean - too much air for the fuel - and not moving from it. This sensor controls fuelling, and a healthy one switches constantly as the module hunts either side of the ideal mixture. One that sits still has usually stopped responding, though it can also be reporting a real problem it cannot see past.
Possible causes
- CommonAged or contaminated oxygen sensor
- CommonExhaust leak upstream of the sensor
- CommonSensor poisoned by oil, coolant or silicone sealant
- CommonWiring or connector fault
- PossibleGenuine mixture problem - a vacuum leak, a fuel delivery fault, a leaking injector
- PossibleHeater circuit fault, so the sensor never reaches working temperature
What you might notice
- Check engine light on
- Worse fuel economy
- Failed emissions test
- Rough running or hesitation
- Black smoke in the rich case
What to check, in order
- Watch the sensor on the live data screen with the engine warm. An upstream sensor should switch several times a second at idle - one that sits at a fixed value has stopped working.
- Check for exhaust leaks upstream of the sensor. Air drawn in through a leak makes a working sensor report lean.
- Read all codes. Fuel trim codes alongside this one suggest the mixture really is wrong.
- Check the sensor's heater circuit - a sensor that never gets hot never starts switching.
- Ask whether silicone sealant was used recently. It poisons oxygen sensors permanently.
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