What it means
Exhaust Gas Temperature Sensor 2/3 Correlation (Bank 1): the value does not correlate with the related sensor or expected pattern. The ECU uses this temperature to protect the catalyst and diesel particulate filter.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Bank 1 EGT sensors 2 and 3 measure exhaust heat at separate points used by the module to protect the catalyst and DPF. This code sets when their readings fail the expected correlation check under qualifying conditions; a drifting sensor, a circuit problem, or a real temperature difference caused by an exhaust leak can produce that mismatch.
Common causes
Most likely first.
- One exhaust-gas temperature sensor has drifted or failed
- Damaged sensor wiring or connector
- Exhaust leak or unusual temperature difference between sensor locations
Symptoms
- Check-engine light on
- DPF regeneration may be affected
- Reduced engine power in some vehicles
How to diagnose it
- Record freeze-frame data and compare live bank 1 EGT sensor 2 and 3 readings through warm-up to identify which reading is implausible or diverges.
- Inspect the sensor 2 and sensor 3 connectors and wiring for heat damage, corrosion, loose connections, or chafing.
- Look for an exhaust leak or damaged joint between the two sensor locations that could create an unusual temperature difference.
- Check that both sensors are correctly installed in their specified bank 1 positions.
- Test each sensor and circuit against the manufacturer’s specification, checking the wiring before condemning either sensor.
- If these checks pass, investigate a control-module fault or applicable update using vehicle-specific service information.
Common fixes
- Repair damaged wiring or connector terminals for bank 1 EGT sensor 2 or 3.
- Repair an exhaust leak between sensor positions 2 and 3.
- Reinstall a sensor that is incorrectly fitted or positioned.
- Replace the sensor confirmed by testing to be inaccurate.
- Correct a confirmed control-module fault or applicable software issue.
Can I keep driving?
If there is no power loss or active aftertreatment warning, a short, gentle trip for diagnosis may be reasonable. Limit driving if DPF regeneration is disrupted or power is reduced, because continued operation may allow soot loading to rise or trigger a stronger restriction.
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.