Engine Exhaust Temperature Sensor 2 Circuit High
The exhaust temperature sensor 2 is reporting a high circuit voltage.
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What it means (plain English)
Inside the ECU, the exhaust temperature sensor 2 measures the temperature of the exhaust gas. It sends a voltage signal back to the ECU, typically between 0.5 to 4.5 volts, representing different temperature levels. If this voltage goes above the expected range, the ECU triggers a fault code.
What the computer is actually seeing
The ECU is designed to read a specific voltage range from the exhaust temperature sensor. When it sees a voltage exceeding approximately 4.5 volts, it considers this a fault and sets code SPN 3349.
What a healthy reading looks like
Expected voltage from the exhaust temperature sensor should be between 0.5V and 4.5V under normal operating conditions. Temperatures can range from 300°F (149°C) to above 1500°F (815°C) depending on the engine load.
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 for the exhaust temperature sensor 2. Check for frays, corrosion, or loose connections. If damaged, repair or replace as needed.
- 22. Measure the voltage at the exhaust temperature sensor connector with a multimeter. The correct range should be 0.5V to 4.5V. If voltage is above 4.5V, proceed to the next step. If below, recheck sensor and wiring.
- 33. Disconnect the exhaust temperature sensor and measure resistance across the sensor terminals. The resistance should be within the sensor manufacturer's specifications. If it’s open or shorted, replace the sensor.
- 44. Inspect the exhaust system for any leaks or issues that could be affecting temperature readings. Repair any leaks found.
Common causes
- Wiring harness short to voltage
- Faulty exhaust temperature sensor
- Bad ECU connection
- Exhaust pipe leaks affecting temperature readings
- Damaged insulation on sensor wiring
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code present?
It's generally safe to drive but may lead to overheating issues if ignored, especially under heavy loads.
Will this code return after clearing it?
If the issue causing the high voltage is not fixed, the code will likely return.
Why does this code pair with others?
When there’s a fault in the exhaust system, it can trigger multiple codes related to exhaust temperature sensors.
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