'07 W211 E320- P0544 code
 

My friend just got an '07 E320 (replacement for identical crashed car), and it threw a P0544 code= Bank one sensor circuit exhaust gas temperature sensor. Anyone know where that is located on this car? Is it something that can be cleaned? The car has a warranty, but was purchased out of state. It may be more of a hassle to deal with the warranty if it is something simple or inexpensive to fix. I have not checked to see if it has the famous "oil cooler seal" leak (80,000 miles on the car), but if it does, it will be under warranty. If so, the sensor problem will get fixed at the same time......Rich

EGT sensors are under the car with the cat. Easy to get to once it's up in the air.

There are two temperature sensors and a differential pressure sensor. The temperature sensors thread into the pipe ahead of the cat, and the cat body itself. The delta P has two hoses on two pipe stubs to a module tucked away near the cat.

When ours went out (threw the same code IIRC) on the 08 I just went ahead and replaced both, since I wasn't sure, despite having WIS, which one it was. I did not have my Star computer at that time. I figured that if one died, the other was about to follow.

I think the sensors ran about $100 each.

I hit the nuts with a little AeroKroil and they backed right out. Easy Peasy. The wires are permanently attached to the sensor, and the other end goes to a harness plug tucked away near the engine.

The wiring was a little fussy getting it routed and clipped back into position but other than that, took me about an hour.

Pro tip - that cat gets HOT and stays HOT for a long time...

One more thing that should be done on principle to a 10 year old OM642:

http://www.peachparts.com/shopforum/diesel-discussion/378195-om-642-camshaft-position-sensor-replacement.html

Simple to change but if it fails you are dead in the water.