What it means
The bank 1 sensor 2 EGT reading deviates from the expected ratio against the upstream EGT sensor or modeled exhaust temperature. Confuses DPF regeneration control and may force a forced regen.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 sensor 2 measures exhaust gas temperature farther downstream than sensor 1 in the same bank, helping the control module assess aftertreatment and DPF regeneration conditions. The module compares its reading with the upstream temperature and the expected exhaust temperature pattern. P2084 sets when the reading is electrically plausible but does not follow that relationship, which can point to a drifting sensor or an abnormal temperature gradient from a heavily loaded DPF.
Common causes
Most likely first.
- Sensor aged or drifting
- DPF heavily loaded — non-physical temperature gradient
- Sensor element aged beyond calibration window
Symptoms
- Check-engine light
- Possible reduced engine performance
- Possible exhaust or emissions-system warning
How to diagnose it
- Read freeze-frame data and note regeneration status, then compare bank 1 sensor 2 EGT with bank 1 sensor 1 and other available temperature readings.
- Inspect the bank 1 sensor 2 connector and downstream harness for heat damage, corrosion, looseness, or chafing.
- Check that bank 1 sensor 2 is securely mounted and positioned as intended in the exhaust.
- Compare sensor readings through the manufacturer's specified operating conditions, including regeneration where applicable, to distinguish a slow sensor from an abnormal exhaust temperature gradient.
- If the sensor circuit and mounting are sound, check DPF loading and related aftertreatment data using the manufacturer's diagnostic procedure.
Common fixes
- Repair a loose connector or damaged bank 1 sensor 2 wiring.
- Secure the sensor in its exhaust mounting.
- Replace bank 1 sensor 2 if its response fails the manufacturer's test.
- Correct excessive DPF loading using the vehicle's approved service procedure.
- Repair any other confirmed aftertreatment fault causing the abnormal temperature gradient.
Can I keep driving?
If the engine runs normally, drive gently and avoid towing or extended high-load trips until the cause is checked. A faulty downstream temperature reading or a heavily loaded DPF can disrupt regeneration and may lead to reduced power.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.