What it means
Exhaust Gas Temperature Sensor 1/3 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
On bank 1, EGT sensors 1 and 3 provide exhaust-temperature readings the control module uses to manage catalyst and DPF protection. This code sets when the comparison between those two readings falls outside the expected pattern under the monitor’s operating conditions, which can happen if a sensor drifts or an exhaust leak changes the temperature between their locations.
Common causes
Most likely first.
- One EGT sensor drifts
- Exhaust leak between the two sensor positions
Symptoms
- Check-engine light on
- DPF regeneration may be affected
- Reduced engine power in some vehicles
How to diagnose it
- Read freeze-frame data and graph bank 1 EGT sensors 1 and 3 during a cold start and warm-up to see whether one reading is implausible or separates from the expected trend.
- Inspect the connectors and heat-exposed wiring for bank 1 sensors 1 and 3 for chafing, melted insulation, corrosion, or loose terminals.
- Check for exhaust leaks between the sensor locations, paying attention to soot marks or damaged joints.
- Confirm both sensors are fitted in their correct bank 1 positions and are seated correctly.
- Test the sensors and their circuits according to the manufacturer’s specification to distinguish a drifting sensor from a wiring fault.
- If the readings and circuits pass, use vehicle-specific service information to check for a control-module issue or applicable update.
Common fixes
- Repair damaged wiring or a poor connector at bank 1 EGT sensor 1 or 3.
- Seal an exhaust leak between the two sensor positions.
- Correct sensor placement or installation if either sensor is in the wrong location.
- Replace the sensor that testing identifies as drifting or failed.
- Repair a confirmed control-module fault or apply an applicable update.
Can I keep driving?
A brief, gentle drive may be possible if the engine runs normally and no DPF or power restriction warning is active. Avoid repeated short trips or heavy loads if regeneration is affected or power drops, since the DPF may not manage soot correctly and the vehicle may enter a reduced-power mode.
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.