Mercedes P0544 Code Exhaust Temperature Sensor Problem

Mercedes-Benz vehicles such as GL, ML, R, and Sprinter equipped with diesel engines (including Bluetec) may trigger the check engine light, which fault codes such as P0544, P0546, P2201, or P2031 pointing to a bad Exhaust Gas Temperature Sensor Circuit.

If data is read from the sensor, you may get an error sensor out of range and a code for B19, B19/9, and B19/11, also known as TWC temperature sensor, error code 249 f. Even if you clear the code, it usually returns after a few days. In a few cases, the vehicle may go into limp mode when this fault code is triggered.

The sensor may work as designed when it cools down, but it does not provide the correct temperature reading once the engine and catalytic converter warm up. To diagnose the sensor’s performance, allow the engine to warm up to operating temperature. The temperature from these sensors should be in the 450 to 700 degree F range.

A defective exhaust temperature sensor often causes this problem (also known as B19, B19/9, which may have various part numbers such as A005 153 40 28 or A007 153 74 28, A 005-153-45-28, A 007-153-63-28. Call your Mercedes-Benz dealer and provide the VIN to verify the part number. The typical cost to change one of the sensors ranges from $300 to $480. Your Mercedes-Benz can have up to four sensors. Built upon the sensor can hinder its performance. The sensor can be replaced, or cleaning the sensor can sometimes fix this problem.

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What you will need

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• Mercedes Exhaust Temperature Sensor
• 17mm short open-end wrench

Procedure

1. Raise the car at the front. Use a jack stand or ramps.
2. Remove the soundproof shield to access the catalytic converter and exhaust pipes. 
3. Locate the exhaust temperature sensor. There are two to three exhaust temperature sensors on Mercedes diesel models and Dodge Sprinters.  Which sensor needs to be replaced depends on the fault code. Mercedes Exhaust Temperature Sensor
4. Loosen the 17mm nut and pull it away from the sensor. A stubby 17mm wrench makes removing the sensor much easier.
5. Remove the sensor from the exhaust, DPF, or catalytic converter. Note that the sensor tip is long. Do not bend the sensor part. 
6. Remove any clips that hold the wire in place. In this case, a zip tie was used to hold the wire. A long screwdriver was used to cut the zip tie due to space constraints. 
7. Unplug the electrical connector. 
8. Install a new exhaust temperature sensor in reverse order.

Solution 2 – Cleaning Mercedes Exhaust Temperature Sensor

It is possible to remove the sensor and clean it. You will need to use Sensor Safe Spray Cleaner to remove any built-upon sensor element. Blow air on the sensor element to clean it.

Cleaning the sensor may not always work. There is a high chance that the problem will return in a few months.

Check electrical connector

If you clean the sensor or replace it, the code returns; ensure that the electrical connector is not saturated with oil or that the wire harness is not damaged.

We hope you find the Mercedes P0544 Code Exhaust Temperature Sensor Problem guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.