BMW Hard Start and Multiple DME Codes after Thermostat Replaced
Vehicle: 2007 BMW 760Li
(E66), V12-6.0L (N73TU), Automatic Transmission
Problem: The vehicle owner asked the shop
to replace the coolant and thermostat using the aftermarket part
he provided. The technician installed the thermostat and replaced
the coolant, but after the job was completed, the engine became
hard to start and the malfunction indicator light (MIL) came on.
Details: When the technician connected the
scan tool, he retrieved the following diagnostic trouble codes
2B5C – P0335 – DME2: Crankshaft Sensor signal
2D0F – P0100 – DME2: Air-mass Sensor, Bank 2 signal
2EF5 – P0598 – DME: Map Thermostat activation
2A80 – P2088 – DME2: Inlet VANOS Bank 2 activation
2A85 – P2090 – DME2: Exhaust VANOS Bank 2 activation
The technician rechecked all his work and everything seemed to be
fine. He called ALLDATA Tech-Assist for advice. The Tech-Assist
consultant told the technician that there had been many reports
of problems using aftermarket thermostats on these vehicles,
which included hard starting, extended engine cranking times, and
The consultant suggested disconnecting the thermostat electrical
connector, clearing the DTCs and see which DTCs reset or change.
He also advised to verify that fuse 006 in the integrated supply
module, located at the right rear of the engine compartment, was
The technician checked fuse 006 and it was open. He installed
another fuse and it popped immediately. When he connected the old
thermostat, the fuse did not pop.
Confirmed Repair: The tech ordered a new
thermostat from BMW and installed it. As it turned out, the
aftermarket thermostat was causing the multiple DTCs, the hard
start and fuse 006 to blow. After the repairs, the engine started
and ran normally, fuse 006 was fine, the DTCs were cleared and
they did not return. Fixed!