P2031: Exhaust Gas Temperature Sensor Circuit — Bank 1 Sensor 2
What to do
Expect the particulate filter warning to appear eventually even if it has not yet, because the car will stop running its cleaning cycle without a temperature reading it trusts. If a filter has already been replaced and the problem came back, mention it — that pattern points here rather than at the filter.
What this code means
A fault in the second exhaust gas temperature sensor on bank 1. These sensors are placed through the aftertreatment system — before the turbo, before the catalyst, before and after the particulate filter — and the module reads them together to know how hot each stage is.
Their most important job is governing particulate filter regeneration, and that gives this code a consequence that is not obvious from its name. Regeneration means deliberately raising exhaust temperature to around six hundred degrees for several minutes, which is a genuinely dangerous thing to do blind: too cool and the soot does not burn, too hot and the filter substrate can melt. The module will therefore not command a regeneration it cannot monitor.
So the practical result of a failed exhaust temperature sensor is a particulate filter that gradually blocks, because the cleaning cycle it depends on is no longer being run. A vehicle that keeps reporting a blocked filter, on which the filter has already been replaced, is a strong candidate for an exhaust temperature sensor fault — the filter was never the problem.
These sensors live in the harshest environment on the vehicle and their wiring runs along the exhaust, so heat damage to the harness is at least as common as the sensor itself failing.
Likely causes
Start here
- Faulty exhaust gas temperature sensor · moderate
- Heat damage to sensor or wiring · moderate
- Corroded or loose connector · easy
Less common
- Open circuit in sensor wiring · moderate
- Seized sensor thread in the exhaust · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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