P2379: O2 Sensor Out of Range During Deceleration Bank 2 Sensor 2
What to do
Symptomless as a rule, and often an early warning rather than a failure — the same code family P2297 describes as more sensitive than the ordinary sensor tests. Exhaust joints checked first, then the bank-to-bank comparison, before the sensor is priced.
What this code means
The downstream sensor on bank 2 failed the overrun test — the free reference condition P2297 explains, applied at the position after the catalyst.
On overrun the module cuts fuel entirely and near-plain air flows through the engine, the catalyst and past every sensor — a known test gas manufactured every time the driver lifts off. A downstream sensor failing it adds a nuance sensor 1's version lacks: the air reaches this sensor through the catalyst, so a sluggish response here can be the sensor ageing or the catalyst's oxygen storage smearing the transition. A sensor that passes the test's timing on the other bank while this one lags is the comparison that separates them — and P2096's exhaust-leak caution applies before either is condemned, since in-drawn air corrupts this measurement the same way it corrupts the trim.
Likely causes
Start here
- Aged or lazy downstream oxygen sensor · moderate
- Exhaust leak before the sensor · easy
Less common
- Failed catalytic converter · specialist
Symptoms
Components involved
Information, not instruction
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Community experience
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