Engine Exhaust Temperature Sensor 1 Low
Low voltage reading from the engine exhaust temperature sensor 1.
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What it means (plain English)
The engine exhaust temperature sensor 1 is measuring lower than expected temperatures, which could indicate a faulty sensor, bad wiring, or exhaust leaks.
What the computer is actually seeing
The engine control unit (ECU) expects the exhaust temperature sensor 1 to provide a voltage signal that reflects exhaust temperatures typically between 250°F to 1200°F (120°C to 650°C). If the voltage falls below the manufacturer's specified threshold (often under 0.3 volts when it should be higher), it triggers this code.
What a healthy reading looks like
Expect the exhaust temperature to be around 300°F (150°C) when idling and can rise to about 1200°F (650°C) under load. The sensor typically sends a voltage between 0.5V to 5V corresponding to these temperature ranges.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connector to the engine exhaust temperature sensor 1 for damage or corrosion. Repair as needed. Decision: Are the wiring and connector in good condition? Yes -> Go to step 2. No -> Repair or replace wiring/connectors; recheck code.
- 22. Measure the voltage at the exhaust temperature sensor 1 while the engine is running. Expected voltage should be between 0.5V and 5V. Decision: Is the voltage in the expected range? Yes -> Go to step 3. No -> Replace the exhaust temperature sensor 1 and recheck code.
- 33. Check for exhaust leaks before the exhaust temperature sensor. Use smoke or soapy water to check joints and gaskets. Decision: Are there exhaust leaks? Yes -> Repair exhaust leaks and recheck code. No -> Go to step 4.
- 44. Check for software updates or faults in the engine control module (ECM). Decision: Any faults found? Yes -> Follow diagnostic steps for ECM fault. No -> This may indicate a need for ECM replacement. Proceed accordingly.
Common causes
- Faulty exhaust temperature sensor 1
- Open or shorted wiring to the sensor
- Exhaust leaks before the sensor
- Faulty engine control module (ECM)
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally drivable, but you should fix it soon to avoid potential engine performance issues.
Will the code come back after repairs?
If the underlying issue is fixed, it shouldn't return. Monitor after repair.
Why does this code pair with others?
Often, multiple sensors in the exhaust system work together, and faults can affect readings across several sensors.
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