Help! What did I do? '08 X358 with 83k miles. Thought I'd pull the spark plugs to take a look at them to help diagnose an intermittent rich issue. Went ahead and replaced them while they were out anyway with new NGK iridium.

Started it back up, runs smooth enough, but now temp gauge isn't registering at all. When OBD reported temp climbing over 180, I shut it off.

What have I knocked loose or forgotten to reattach? I've looked everywhere and I'm clueless. Any suggestions? THANKS!

 

Was the coolant temp very high?

If not temp gauge sensor is located in the plastic manifold at the top of the engine.

Try replacing that first but check wiring too.

Fault may be stepper motor on dash which would be more problematic.

 

Thanks. I'll look again and focus on the temp sensor. Maybe I knocked a wire loose and just missed it. Is there more than one sensor? I mean, would one (that's unplugged) report to the gauge while another reports to the computer? At least according to my scanner, the computer thinks the temp is rising, but the gauge never moves.

 

Don't rely on the instrument cluster gauge to determine coolant temperature. The gauge doesn't move between 95 C and 128 C, which is a problem.

Normal operating temperature of the AJ33/AJ34 is 95 C to 102 C.

 

Your code reader should be able to read the temperature of the coolant for you.
This is a much better way to see what temperature is than the gauge.