The ¡°Check Engine Light¡± started coming up on my 1994 850 Turbo since June this year. I brought my car to a local dealer and came up with a code ¡°4-3-3¡±. I had replaced a Knock sensor by their suggestion. But 10 days later, the light came up again. I went back to dealer again, they told me it was a result of bad fuels. I kept using Sunoco 94 afterwards, but it didn¡¯t change anything. I don¡¯t think the problem is about the knock sensor somehow. I think technicians don¡¯t know how to resolve this problem either.

I was tried to clean this faulty code by myself, but the light still comes up again and again. The car is running good I guess, nothing strange has been found out. I really want to know what to do. Could someone help me here? Thanks ahead.

Jack

I had the same problem on my V70 (98). But instead changing the sensor I replaced distributor cap and rotor, as sometimes knock sensor code may be caused by ignition problem, and it fixed the problem.
Good luck.

On a '94 turbo 850 ONLY, that code is really caused by an internal fuel ECU problem, not bad gas or bad knock sensors. Try to locate a used ECU rather that buy reman as you'ld save some $$$

Earlier posts here referred to a problem in the wiring harness attached to the knock sensors on the early turbo models. The replacement cost is in the neighborhood of $400 or so, but I'm cheap.

When the "Check Engine" light appears and I get the code for the front or rear (usually) sensor error, I can always get another 7500 miles or so before the next warning by unplugging and then replugging the connections (2) nearest the knock sensors - under the exhaust manifold. I usually record the codes and mileage at the time of occurrence to be sure that I don't have an unusual problem flagged by an out-of-sequence error message. Otherwise, clearing the codes means I'm good for another several weeks, with no ill effects on the performance or operation of the car. Hope this helps.

Eddie H.