Exhaust Temperature Sensor 1 Circuit Low
Indicates a low voltage reading from the exhaust temperature sensor 1 circuit.
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What it means (plain English)
The exhaust temperature sensor monitors the temperature of gases coming out of the engine. A low voltage means it’s not detecting normal temperature, which can point to problems in the exhaust system or with the sensor itself.
What the computer is actually seeing
The ECM expects the exhaust temperature sensor to output a voltage range typically between 0.5V to 4.5V, depending on the temperature level. A reading below 0.5V is considered low and triggers the fault code.
What a healthy reading looks like
Expected voltage from the sensor should be around 1V at 200°F and increase to about 4V at 1200°F.
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.
- 1Inspect the wiring and connector for the exhaust temperature sensor for any signs of damage or corrosion. If found, repair or replace as necessary.
- 2Check the sensor resistance with a multimeter while the engine is off. Resistance should be within the manufacturer's specified range (typically 10-50 ohms). If out of range, replace the sensor.
- 3With the engine running, monitor the voltage output from the exhaust temperature sensor with a scan tool. Ensure it is within the expected voltage range (0.5V-4.5V) under normal operating conditions.
Common causes
- Faulty exhaust temperature sensor
- Wiring issues (shorts or breaks)
- Connector problems
- Exhaust gas leaks
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
Yes, but it’s advisable to fix the issue soon to avoid potential damage to exhaust components.
Will this code come back after resetting?
If the underlying cause is not fixed, yes, the code will likely return.
Why does this code come with other SPN codes?
These codes often relate to the same system or component, indicating multiple issues can arise from a common fault.
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