Engine Exhaust Temperature Sensor 1 Circuit Low
The exhaust temperature sensor circuit is reporting a low voltage condition.
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What it means (plain English)
The computer sees that the voltage from the exhaust temperature sensor is lower than it should be, usually below 0.1 volts. It expects a normal range around 0.5 to 4.5 volts depending on the temperature.
What the computer is actually seeing
The engine control module (ECM) is monitoring the exhaust temperature sensor signal, expecting a varying voltage indicating temperature changes. If the voltage drops below a specific threshold (commonly <0.1V), it registers a code.
What a healthy reading looks like
Normal voltage from the exhaust temperature sensor should be between 0.5 to 4.5 volts at operating temperature. Lower than 0.1 volts triggers the fault code.
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.
- 1Check the exhaust temperature sensor wiring for any visible damage or corrosion. Ensure the connectors are secure and clean. If the wiring looks good, move to the next step.
- 2Measure the voltage at the exhaust temperature sensor connector with the ignition on (engine off). You should see a voltage between 0.5 and 4.5 volts. If it's below 0.1 volts, proceed to the next step.
- 3Disconnect the exhaust temperature sensor and check the resistance across its terminals. A typical reading should be a few hundred ohms. If the reading is significantly different, the sensor is likely faulty.
- 4If the sensor tests good, check the wiring continuity from the sensor back to the ECM. Look for breaks or shorts in the wiring. If damaged, repair the wiring and retest.
Common causes
- Faulty exhaust temperature sensor
- Wiring issues in the sensor circuit
- Corroded or damaged connectors
- Open or short circuits in the sensor signal wire
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
Yes, but drivability may be impacted, and emissions can increase.
Will this code come back after resetting?
If the underlying issue isn't fixed, the code will likely return.
Why does this code pair with other SPN codes?
They may indicate related sensor or circuit issues affecting exhaust management.
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