P2096
Post Catalyst Fuel Trim System Too Lean (Bank 1)
- Severity
- Medium
- Driving
- Drivable — book it in
The mixture measured after the catalytic converter on bank 1 is too lean - too much air for the fuel being delivered - and the module has run out of adjustment trying to correct it. The most common cause is not fuelling at all: an exhaust leak between the converter and the sensor lets air in, and the sensor honestly reports a lean mixture that does not exist.
Possible causes
- CommonExhaust leak between the converter and the downstream sensor
- CommonFailing downstream oxygen sensor
- CommonVacuum leak
- PossibleFailing catalytic converter
- PossibleFuel delivery problem - weak pump, blocked filter, dirty injectors
- PossibleUpstream oxygen sensor drifting
What you might notice
- Check engine light on
- Failed emissions test
- Worse fuel economy
- Rough running in some conditions
- Often no symptom the driver notices
What to check, in order
- Check for exhaust leaks first, particularly at the joints and welds around the converter and the sensor. This is the most common cause and it is far cheaper than anything else on the list.
- Read all codes. Upstream fuel trim codes alongside this one mean the mixture really is wrong and the problem is upstream, not after the converter.
- Watch both the upstream and downstream sensor readings on the live data screen.
- Do not replace the catalytic converter on this code alone. It is the most expensive item here and rarely the cause.
- Check for vacuum leaks, which produce a lean condition throughout.
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, air metering and auxiliary emission controls
P2000P2001P2002P2003P2004P2005P2006P2007P2008P2009P2010P2011P2012P2013P2014P2015P2016P2017P2018P2019P2020P2021P2022P2023P2024P2025P2026P2027P2028P2029P2030P2031P2032P2033P2034P2035P2036P2037P2038P2039P2040P2041P2042P2043P2044P2045P2046P2047P2048P2049P2050P2051P2052P2053P2054P2055P2056P2057P2058P2059P2060P2061P2062P2063P2064P2065P2066P2067P2068P2069P2070P2071P2075P2076P2077P2078P2079P2080P2081P2082P2083P2084P2085P2086P2087P2088P2089P2090P2091P2092P2093P2094P2095P2096P2097P2098P2099