Exhaust Gas Temperature Sensor Circuit Low (Bank 2 Sensor 1)
Code P0548 indicates the exhaust gas temperature (EGT) sensor circuit for Bank 2 Sensor 1 is reading lower than expected. This sensor monitors exhaust temperature to help the engine computer optimize combustion and emissions control. A low signal typically means a wiring issue, corroded connector, or failed sensor.
What You Might Notice
- Check Engine Light illuminated
- Possible rough idle or hesitation
- Reduced fuel economy
- Increased emissions
- Potential limp mode activation on some vehicles
Most Common Causes
- 1
Loose or Corroded Connector
The most common cause is a loose, corroded, or damaged connector at the EGT sensor harness. Corrosion prevents proper signal transmission from the sensor to the engine computer.
- 2
Broken or Damaged Wiring
Wires leading to the EGT sensor may be broken, pinched, or have damaged insulation causing a short to ground, resulting in low signal voltage.
- 3
EGT Sensor Failure
The sensor itself may have failed internally, producing an abnormally low or no voltage output regardless of actual exhaust temperature.
- 4
Engine Control Module Failure
Though less common, a faulty PCM or ECM may fail to read the sensor circuit correctly or communicate with the sensor properly.
How to Diagnose It
- 1
Check Loose or Corroded Connector — The most common cause is a loose, corroded, or damaged connector at the EGT sensor harness. Corrosion prevents proper signal transmission from the sensor to the engine computer.
- 2
Check Broken or Damaged Wiring — Wires leading to the EGT sensor may be broken, pinched, or have damaged insulation causing a short to ground, resulting in low signal voltage.
- 3
Check EGT Sensor Failure — The sensor itself may have failed internally, producing an abnormally low or no voltage output regardless of actual exhaust temperature.
- 4
Check Engine Control Module Failure — Though less common, a faulty PCM or ECM may fail to read the sensor circuit correctly or communicate with the sensor properly.
How to Fix It
- 1
Inspect and Clean Connector
Locate the EGT sensor connector on Bank 2 Sensor 1 (typically on the exhaust manifold or catalytic converter area). Disconnect and inspect for corrosion, debris, or damage. Clean contacts with electrical contact cleaner and reconnect firmly.
- 2
Check Wiring and Harness
Visually inspect the wiring harness from the EGT sensor to the engine computer for breaks, cuts, pinches, or areas where insulation is damaged. Repair or replace damaged sections and ensure proper routing away from heat sources.
- 3
Replace EGT Sensor
If connector and wiring are intact, the sensor has likely failed. Remove the old sensor by unbolting it from the exhaust manifold or catalytic converter. Install the new sensor, apply high-temperature anti-seize compound to threads, and reconnect the harness.
- 4
Clear Code and Test Drive
After repairs, use a diagnostic scanner to clear the P0548 code. Take the vehicle on a test drive to verify the sensor signal normalizes and the code does not return.
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