S90 CEL reset after coolant sensor replacement

[Marty M]

I replaced the coolant temperature sensor on my 98 S90 and learned afterwards that the CEL needs to be reset before the radiator fan will start behaving again. I tried the usual "disconnect battery" thing, and then had Autozone reset the light (yes, they did do it), but neither method has cleared the fault code and reset the light. The coolant temp sensor code is the only one showing up on the diagnostic.

Interestingly, it also hasn't helped with resetting the radio which my dopey son locked-out by punching in random codes. I searched the forums and web at length for a procedure to the CEL reset, and can't find a definitive answer. This is maddening!

Step up and be the "hero of the day" for responding with a post that answers what should be the simplest of questions. However, please don't ask me to reset the Service Engine Light or to have the ODBII codes read (like has been said to the other 100 people asking this same reset question).

Thanks in advance. Marty

[billofdurham]

Welcome to Matthew's Volvo Site.

I have never set out to be the "hero of the day" as there are many people better suited than me to receive that accolade.

The only way to reset the CEL on the S90 is with a scan tool through the DLC. If Autozone did this and the code has not cleared then either they did not do it properly or the code came back because of an ongoing problem. Ask them nicely to try again. Failing that try a dealer using the Volvo code reader.

The radio will not reset by disconnecting the battery. This is the procedure from the Owner's Manual:

Anti-theft code

The radio features anti-theft circuitry. If the set is removed from the vehicle or if the battery power is disconnected, a special code must be entered to enable operation of the set.
Refer to the radio code card supplied with your vehicle or ask your retailer for the correct code.
When the car is parked with ignition key removed the anti-theft LED will flash. To enter the code

After installation or when the set has been disconnected from power, the set displays "CODE" when it is switched on.
Enter the 4-digit code using the preset buttons.
If the correct code is entered the set is entered the set is ready to use.
If you enter an incorrect code you must enter the correct code again from the beginning.

Incorrect code

If an incorrect code has been entered "rPt" is displayed. Enter the correct code. After three unsuccessful coding attempts the set will lock and remain locked for two hours.
"OFF" is displayed.
During this waiting period:

the battery must be connected

the ignition key must be turned to position I

the unit must be turned on

Make sure the headlights are turned off to help prevent battery drain (please refer to page 20 for information on turning the headlights off).
Enter the code again once this time has elapsed.

Recently we found that on the 960, which was the predecessor of the S90, the waiting time was mis-printed and should be 24 hours. This may also apply to your car.

Bill.

[Marty M]

Thanks for the write-up Bill. I'll proceed as you suggested and hope for a positive outcome.

Marty