Exhaust Gas Temperature Sensor 3
Exhaust gas temperature sensor 3 is reading out of range.
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What it means (plain English)
The exhaust gas temperature sensor measures how hot the exhaust gases are after the diesel engine. If this sensor detects temperatures above or below the normal operating range, it sets this fault code.
What the computer is actually seeing
The engine control module (ECM) monitors the output voltage of the exhaust gas temperature sensor. In normal conditions, this sensor should output a voltage between 0.5V and 4.5V depending on the temperature. If the reading is consistently out of this voltage range, it will trigger SPN 1744.
What a healthy reading looks like
Expected voltage from the sensor should range from 0.5V (around 150°C / 302°F) to 4.5V (around 700°C / 1292°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.
- 11. Inspect the exhaust gas temperature sensor 3 connector and wiring for damage, corrosion or disconnection. Repair if necessary, then retest.
- 22. Test the voltage output of the exhaust gas temperature sensor with a multimeter. You should see a voltage between 0.5V to 4.5V. If the voltage is outside of this range, proceed to step 3.
- 33. If the sensor output is wrong, replace the exhaust gas temperature sensor 3 and clear the codes. Retest to ensure the new sensor is operating correctly.
- 44. If the sensor output is as expected, check for any active short circuits or open circuits in the wiring harness leading back to the ECM.
Common causes
- Faulty exhaust gas temperature sensor 3
- Open or shorted wiring to the sensor
- Corrosion in the connector terminals
- Excessive exhaust heat damaging the sensor
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; you can drive the vehicle but should fix it soon to avoid possible engine performance issues.
Will this code come back after clearing?
If the underlying issue is not fixed, yes, the code will likely return.
Why does it pair with other SPN codes?
It often indicates related issues with exhaust temperature or sensors, which can be interlinked in the system.
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