What it means
The module detects that the readings from exhaust gas temperature sensors 1 and 2 on bank 1 do not correlate as expected. It sets the code when the difference between their readings exceeds the calibrated limit under monitor conditions.
How it works
Bank 1 has two exhaust gas temperature (EGT) sensors whose readings help the control module track exhaust heat for aftertreatment protection. During the correlation monitor, the module compares sensors 1 and 2; this code sets when their difference exceeds the allowed limit under the monitor’s operating conditions.
Common causes
Most likely first.
- Faulty exhaust temperature sensor
- Damaged wiring or connector
- Exhaust leak affecting temperature readings
- Sensor installation or location issue
- Control module fault
Symptoms
- Check engine light
- Reduced engine power
- Increased emissions
- Possible exhaust aftertreatment warning
How to diagnose it
- Use a scan tool to record freeze-frame data and compare live readings from bank 1 EGT sensors 1 and 2 as the exhaust warms, looking for a reading that is implausible or diverges from the other.
- With the exhaust cool, inspect both sensor connectors and wiring for heat damage, corrosion, loose pins, or contact with the exhaust.
- Check for soot traces or other signs of an exhaust leak between the two sensor locations, since a leak can change the temperature reaching one sensor.
- Verify that sensors 1 and 2 are installed in the correct bank 1 positions and are seated as specified by the manufacturer.
- Test each sensor and its circuit against the manufacturer’s specification, including continuity and connector condition, before replacing a sensor.
- If the sensors, wiring, installation, and exhaust are sound, check for applicable control-module updates or faults using vehicle-specific service information.
Common fixes
- Repair a loose, corroded, or heat-damaged connector or wiring section at bank 1 sensor 1 or 2.
- Repair an exhaust leak between bank 1 EGT sensor positions 1 and 2.
- Correct an incorrectly installed or misplaced sensor.
- Replace the bank 1 EGT sensor shown by testing to be inaccurate.
- Address a confirmed control-module fault or applicable software issue.
Can I keep driving?
If the engine runs normally and no warning indicates an imminent restriction, a short, gentle drive to arrange diagnosis may be possible. Avoid heavy loads or extended driving if power is reduced or an aftertreatment warning appears, because unreliable temperature readings can interfere with emissions-system protection or regeneration.
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.