My father in laws 98 s500 keeps triggering the CEL and error coding the o2 sensor. The sensors are all new and one keeps triggering the light. Even after checking with a second new sensor....same problem.

The car is at the MB dealer, and they are stumped. No broken wires.... and the fault signal jumps up & down, rather than a dead break in a wire somewhere.
ANY IDEAS??? Ever seen before?

What are the codes? There are 5 different O2 codes for each of the 4 O2 sensors on that car!!

Many O2 codes that occur don't mean that the sensor is defective but point to another problem.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator