Exhaust Gas Temperature Sensor 1 Out of Range
The exhaust gas temperature sensor is reporting a temperature outside the expected range.
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What it means (plain English)
The exhaust gas temperature sensor measures how hot the exhaust gases are, which helps control emissions and turbo performance. If the temperature it reads is too high or too low, it can cause the engine control to react improperly and affect engine performance.
What the computer is actually seeing
The engine control module (ECM) monitors the exhaust gas temperature through Sensor 1. If it sees a voltage signal representing a temperature below -40°C (-40°F) or above 1,000°C (1,832°F), it triggers the code SPN 2172.
What a healthy reading looks like
The expected voltage from the sensor should range between 0.5V (approximately 200°C) and 1.5V (around 700°C). Above or below these values can trigger 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 for the exhaust gas temperature sensor. Look for wear, corrosion, or loose connections.
- 22. Measure the voltage at the exhaust gas temperature sensor while the engine is running. Verify it is within the expected 0.5V to 1.5V range.
- 33. If the voltage is out of range, replace the sensor and clear the fault code. Test drive to confirm the issue is resolved.
- 44. If the voltage is normal, check for any exhaust leaks near the sensor that could affect readings.
- 55. If no leaks are found, consider checking the ECM for updates or faults before replacing.
Common causes
- Faulty exhaust gas temperature sensor
- Wiring issues (shorts or opens)
- Corroded connectors
- Exhaust system leaks
- Failed ECM software
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's advisable to fix this soon, as it may affect emissions and engine performance.
Will the code come back after clearing?
If the underlying issue isn't resolved, yes, it will typically return.
Why does this code come with a different SPN code?
Multiple SPN codes can stem from the same issue, particularly in exhaust temperature monitoring.
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