Exhaust Gas Temperature Sensor 1 Circuit Low Input
The ECM detects a low voltage from the exhaust gas temperature sensor 1.
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What it means (plain English)
The exhaust gas temperature sensor 1 is sending a voltage below its normal levels, signaling to the engine control module (ECM) that the temperature of the exhaust gases is lower than expected, typically below 0.5 volts.
What the computer is actually seeing
The ECM sees a voltage signal from the exhaust gas temperature sensor 1 that is significantly below its expected range, indicating cooler-than-expected exhaust temperatures.
What a healthy reading looks like
Normal voltage from the exhaust gas temperature sensor should range between 0.5V to 2.5V depending on the exhaust temperature; a reading below 0.5V indicates a fault.
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. Check the wiring and connectors of the exhaust gas temperature sensor 1 for any visible damage or corrosion. If damaged, repair or replace as necessary. Decision: Is wiring intact? Yes: Go to step 2; No: Repair wiring.
Common causes
- Faulty exhaust gas temperature sensor 1
- Open or shorted wiring in the sensor circuit
- Poor connection or corroded terminals
- ECM software or configuration issues
Typical repair cost
$$
Related codes
Frequently asked questions
Can I drive with this code active?
It can impact vehicle performance, so it's best to address the issue soon.
Will this code come back after I clear it?
If the underlying problem isn't fixed, yes.
Why does this code pair with SPN 5391?
They both relate to exhaust gas temperature sensor issues, often due to related circuit faults.
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