bigben320e

Okay, so my CLS63 has gotten some miles on her and I got a P0128 code CEL. I know this is the thermostat deal, engine coolant temp too low. My indie changed it, Bremen Autowerks. So after some miles, the CEL again, same code, cleared the code, it came back. Bremen changed the thermostat again, as it was under warranty of course, they were thinking possible faulty thermostat.

Fast forward to today, the damn CEL is on again with the same P0128 code! What is the problem? Someone give me some insight, I started thinking possible coolant temp sensor? What?

Plutoe

Post your VIN bigguy!!

bigben320e

VIN WDDDJ77X39A151003

Launchstation

I've had this problem before. Turned out that the ambient air temperature sensor (located in the front lower mesh grille) had fallen out of its rubber grommet holder/bracket and onto the plastic under-body skidpan. It wasn't coming into contact with the oncoming airflow and the engine's radiant heat was causing it to give false readings and play havoc with the vehicles ECU. After mounting it back into the rubber grommet and driving a few miles, the fault promptly went away and has not returned (been well over a year now). It may not be your problem, but it can't hurt to visually check that the sensor is in the little bracket where it's supposed to be and NOT resting in the skid pan.

bigben320e

I will take a look into that, taking it back over to Bremen, as it is is under warranty with the thermostat. I will mention this, as I do look over the car and inspect things myself as well.

Thanks!