SPN 2994 - Engine Exhaust Temperature Sensor 2
Indicates an issue with the second engine exhaust temperature sensor.
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What it means (plain English)
The second exhaust temperature sensor is not reading temperatures as expected, which may indicate a problem with the sensor or the wiring connected to it.
What the computer is actually seeing
The ECM is receiving voltage signals from the exhaust temperature sensor that are outside the expected range, typically less than 0.25V or greater than 4.5V.
What a healthy reading looks like
Expected signal from the exhaust temperature sensor should be between 0.5V and 4.5V, corresponding to a temperature range of -40°C to 1000°C.
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 connectors of the exhaust temperature sensor for damage or corrosion. If any issues are found, repair them and retest.
- 22. Measure the voltage at the sensor connector with the engine at normal operating temperature. You should expect a signal between 0.5V and 4.5V. If the voltage is not within this range, proceed to the next step.
- 33. Using a scan tool, clear the code and monitor the live data. If the code returns, replace the exhaust temperature sensor and retest.
- 44. After replacement, recheck the voltage to ensure it is within the expected range. If it is not, inspect the wiring and ECM connection.
Common causes
- Faulty exhaust temperature sensor
- Wiring issues (short or open circuit)
- Poor connector contact
- Excessive heat exposure causing sensor failure
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code active?
It's generally safe to drive, but you should repair it soon to avoid damage to exhaust components.
Will this code come back after clearing?
If the underlying issue is not fixed, the code will likely return.
Why does this problem sometimes occur with turbo-related codes?
Exhaust temperature sensors can be affected by turbo operation, as high exhaust temperatures impact readings.
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