Mercedes-Benz bulletin LI20.10-P-072886

Complaint Check Engine Light ON with DTC P012800 "The Coolant Temperature is Below the Specified Temperature" active and/or stored in the ME (N3/10). There are no drivability concerns related to this complaint. Cause Root cause varies Remedy Prior to performing any repairs for this complaint: With a cold engine, pressurize the high temp coolant circuit and while it's under pressure, release the cap on the low temp coolant circuit and check if the pressure drops right away or not. If the pressure drops, the lower coolant hoses are swapped. Correct this, fill, bleed and test drive the vehicle. If the complaint returns, then continue with the steps below. IMPORTANT: Use VMI to check for the following emission extended warranty –> Engine Thermostat (incl. software update) MY19-23, Various Models and Platforms (167, 190, 205, 213, 217, 222, 223, 232, 253, 290, 463) If the vehicle is covered under the above emission extended warranty, please perform steps outlined in the accompanying NCU prior to those outlined in this document. If vehicle is not covered under the above emission extended warranty or the complaint continues to occur, then proceed as follows: Check for available software updates to the ME (N3/10). If updated software is available, perform the update, clear the DTC and the perform each of the "WARM START" and "COLD START" test drives listed below twice. If the code does not re-appear then release the vehicle. If there is no new software available OR the DTC returns after the test drives then perform the following steps: • Drain the coolant through a fine mesh sieve and check for signs of debris. Additionally, inspect the coolant reservoir for debris. If any debris is found take pictures of the reservoir and the mesh filter and "flush" the system at least 2-3 times to clear as much of the debris as possible • Replace the thermostat and bleed the system as outlined in AR20.00-P-1142-04A, evacuate the system for 20-30 minutes instead of the 5 minutes specified in step 22 • NOTE: Please use all the tools specified in the AR document. The DTC will continue to populate if the circuit is not properly bled • NOTE: There are two valid thermostats to choose from in the parts section of this LI. Please verify which PN is applicable for the vehicle being worked on via XENTRY Parts Information • After bleeding the system clear the DTC and perform each