Apologies if this question was already dealt with, but the site's search engine turned nothing up, so here goes. Am am consistently getting code 433 on my '94 850T. It has got something to do with the signal from the rear knock sensor, but I do not know how to check this. I have replaced all rubber elbows, so I am almost certain that it is not a vacuum leak. Just did the 120K service and everything service-related has been replaced, except the 02 sensors. Any thoughts on how what to check? Thanks

UnVinRouge

Often it's not the knock sensor but your ignition. Last year I replaced spark plugs, air filter, cleaned distributor cap and rotor and got the fault right away. After clearing it returned couple of times but after changing distributor cap and rotor, and making sure all the spark plug wires were OK it finally went away.
Good luck.

Hey,
Dtc 433 for the rear knock sensor is caused by a faulty sensor connector. You can try pulling the connectors off and on about 20 times each. Front and rear.
Then grease the connectors wiht a di-electric grease. If the problem returns, there is service kit available from Volvo retailer. Both knock sensor jobs are a little tricky. Intake manifold off is your best way to access.

Good luck:)
Gazzer

Thanks for the advice. Where are the knock sensor connectors located so I can clean them.

Hey, they are located on the intake side of the block. If you have very skinny arms, you can reach up from bottom behind ac compressor(grease them up, it's tight). Usually it's best just to remove the intake manifold. Good luck:)
Gaz