Hi All,

Well here goes my first post!

I'v got a 94 Volvo 940 with 98,000 miles on it. Recently I got the 1-4-3 check engine light notifying me of a problem with the knock sensor. I erased the codes several time, but the check engine light came back on.

Step 2, I replaced the knock sensor with a new Bosch unit. Reset the computer and drove fine for about a week before the check engine light came on again with the code for the knock sensor.

Step 3, I called a friend at the Volvo dealership and told him the scenario. He said it is probably the 2nd knock sensor unit at the rear/underside of the engine. Hmmm, is this true? Is there even a second knock sensor on a 94' 940 model? If so, where is it located and does anyone know the part number? Is the second knock sensor the same size/part as the knock sensor located under the intake manifold? The knock sensor that I saw and replaced was on the driver side engine block right under the intake manfold. Replaced that, and retightened to 10lbs of torque.

If there is a 2nd knock sensor, then that is probably the problem. If not, then what other options/steps can I take to get the knock sensor warning message to clear. I really don't want to take the car to the dealership.

Thanks for any suggestions in advance!!!

VolvoBiz

I purchased a 95 940 with 98k about 2 months ago. The car ran rough, no power on acceleration, and slight backfire on deceleration. Engine serice light indicated bad knock sensor. Took the one out of my 91 240 (same bosch p/n) and sure enough, cured all the problems. I do not believe there is a 2nd knock sensor on your car. Even if there was, it is awfully suspicious that it went bad one week after the other one. I would check your connection on the one you replaced. Also, double check the bolt spec..10 ft lbs seems low.


You did not say exactly how you "reset the computer." Did you disconnect the battery for 5 minutes or ???

please post your results, it would be interesting if you found another knock sensor.

good luck

You have only one knock sensor, which is under the manifold. Check the wiring connectors to the sensor: deoxidize and protect with silicone grease.