I have owned my 1991 940 GLE wagon for six years and have had a history of problems with the check engine light coming on. Over the years the majority of check engine codes have been associated with the coolant temp sensor, which has been replaced but but never seems to fix the problem for long. Now the check engine light is on permanently and the exhaust smells like the engine is running rich. This is not an intermittent problem any more. A hard failure seems to have occurred. My Volvo mechanic tells me the check engine code is again the coolant temp sensor. He replaced the sensor but the problem still exists. He is advising me that the problem most likely lies with the engine harness, which he says is probably what has been causing my problems all along.

At this point in the cars life I'm not sure I am ready to spring for a new wiring harness. At least I would like to get a second opinion. Is it likely to be the harness? I know my Volvo mechanic would not be in favor of jury rigging but is there not a way to bypass the harness wiring to the coolant temp sensor without replacing the whole harness? Any other ideas? One thing I am worried about is spending the money to replace the harness and finding that the problem is not fixed.


Thanks is advance

 

Yes you can run a wire on the outside of the harness and see if it fixes the problem.I would not do that as a final fix.You can make a wire that goes into the plastic plug and runn along the harness to the coolant temp sensor.That should work nice.Give it a try and see if it fixes the problem.

 

Thanks for your help. Oddly enough the problem has fixed itself... how long it will last I don't know.

JK

 

If it comes back try what I advised.