Knock Sensors were the Culprit
meteg »
Yes my peformance nightmare with non turbo 95 850 has ended.the knock sensors were the culprit.. even there werent any check engine light on I removed the intake manifold, 4 hrs and installed the new sensors had to do some modification because the older sensors have two plugs on them.. but the new ones didnt instead the new ones came with a common connector at the cable end which has 3 pins. anyway I modified the cables of the old sensors and installed the new ones.. and I cant believe this is the same car..
the power, performance everything is amazing..
I know it sounds odd like I said there was no CEL light on however after the replacement the car really runs strong. there was no other possibility left since many components on the car(engine,tranny, other sensors,distributor cap, rotor, plug wires) are new and injectors are cleaned.. so it was kind of a gamble but it has worked.. I was almost going to sell the car if the problem persisted..
I can finally enjoy the car and hope to use it for many more years if there are no accidents or health problems I may have..
findude »
Regarding the CEL not coming on. I’m having this problem now with my 1996 n/a 850. After querying the OBD II with a scanner, I discovered that the sensors were not ready (the monitor read out is “inc”). I’m trying to get the ECU to “learn” again so that the ECU will recognize the monitors from the sensors, but I haven’t managed it yet.
Research suggests a common cause is a shorted sensor, so I’m starting to troubleshoot that.
I even had a Volvo dealer look at the problem: they told me there were no codes (which I already knew) but never told me that the monitors were not ready. From the scanner I borrowed, one has to drill deep into the menus to actually check the monitors. In other words, the lack of an error condition (CEL) is sometimes just an indicator that the monitors associated with the sensors are either not reporting or the ECU is not interpreting the signal. I suppose you could also have a bad CEL light bulb inside the instrument cluster.
Anyway, it’s a frustrating problem. Especially when you know the car has a problem (mine is obviously running rich) and the on board diagnostic system can’t help.
Performance Nightmare Ended (Thank God)
Subscribe to the MVS Newsletter
The MVS Volvo Newsletter is a once-a-month email delivered to your email. It’s simple to unsubscribe at any time if you change your mind.
Last Updated on December 20, 2025
