Exhaust Gas Temperature Sensor Circuit High (Bank 1 Sensor 1)

Possible causes

• CommonFailed exhaust gas temperature sensor
• CommonCorroded connector - these sit in the hottest, dirtiest part of the vehicle
• CommonWiring damaged by exhaust heat
• PossibleSensor tip damaged or coated with soot
• PossibleSensor seized in the exhaust and damaged during a previous removal
• PossibleLoss of reference voltage or earth

What you might notice

• Reduced power or limp mode
• Particulate filter warning
• Regeneration not happening, so the filter gradually blocks
• Excessive smoke
• Check engine light on

What to check, in order

1. Compare the reported temperature with ambient on an engine that has stood overnight - they should be close.
2. Inspect the connector for corrosion and heat damage. These connectors live in the worst environment on the vehicle.
3. Check the wiring where it runs along the exhaust.
4. Read all codes. Particulate filter codes alongside this one matter more, because a filter that cannot regenerate will eventually block completely.
5. Expect the sensor to be seized in the exhaust. Penetrating oil and patience are worth more than force - a snapped sensor turns a small job into a large one.