Knock sensor madness on '94 850 Turbo Topic is solved

Bflat · Post by **Bflat** » 25 Nov 2005, 19:06

I purchased high-milage (300,000km) '94 850 Turbo wagon (Canadian) about six months ago. It is extremely clean and checked out well with no problems on a pre-purchase mechanical.

The engine check light came on soon after I brought it home. Had it reset several times to verify code fault - initial and subsequent codes read oxygen sensor - sensor replaced. Not that long after the check light was on again. Code said knock sensor. Reset several times - always read knock sensor. Replaced knock sensor. Advised to start using highest octane fuel - done. Light was soon on again. Several resets. Codes always read knock sensor. Last time in, mechanic at my Volvo dealership said he thought he discovered a bad connection. Reset. Light on again a week later. Shop now suggests I bring it back and see if it's the engine management module.

Throughout this madness it has continued to run flawlessly. I'm thinking there was never a problem with the knock sensor ($500), or anything else, in the first place and that the system is just super-finicky after 300,000km. Am going stark raving loonie and although I still enjoy driving it, am cursing the day I bought this crate.

Is there some way to disconnect the light and is that a good ideas?

Any other thoughts?

White850Turbo · Post by **White850Turbo** » 26 Nov 2005, 03:00

Volvo updated the way that the knock sensors work for the 850's. They sell a service kit which includes the newer and updated design. Do you happen to know if this kit was installed?

Bflat · Post by **Bflat** » 27 Nov 2005, 23:33

Thanks for responding Sean.

Yes, the new sensor kit they installed was one of the newer modified ones. Is that significant?

Bflat · Post by **Bflat** » 29 Nov 2005, 00:19

A new development - today, as I was driving, the light went off.

I seem to remember reading in one of the posts (I can't find it now) that the light will reset itself after a period of time.

Is this correct?

Anyone?

White850Turbo · Post by **White850Turbo** » 29 Nov 2005, 07:33

Bflat wrote:A new development - today, as I was driving, the light went off.

I seem to remember reading in one of the posts (I can't find it now) that the light will reset itself after a period of time.

Is this correct?

Anyone?

After a certain number of trouble free driving cycles, the light will turn itself off depending on the nature of the code.

Bflat · Post by **Bflat** » 30 Nov 2005, 14:57

Thanks Sean.

I'm curious - what is an 854 (as opposed to an 850) and how has it been modified?

Post by **matthew1** » 30 Nov 2005, 16:09

Four door (sedan) as opposed to 855, five door (wagon).

Purely a user designation. I don't believe Volvo badged 850s as "854" or "855", although I met a guy with an 855 who had a 855 badge made. His 855 was recently in a Swedespeed.com feature. The Volvo has Mercedes wheels.

White850Turbo · Post by **White850Turbo** » 01 Dec 2005, 06:38

Bflat wrote:Thanks Sean.

I'm curious - what is an 854 (as opposed to an 850) and how has it been modified?

It's modified enough to embarass owners of LT1 V8 Trans-Ams, SS Camaro's, and make it into the November issue of GrassRoots Motorsports Magazine

.

Here's a recent pic of it:

Guest · Post by **Guest** » 06 Dec 2005, 01:02

That's one lean, mean machine!

Bflat

rush · Post by **rush** » 07 Dec 2005, 13:54

what is effected by "Knock sensor" i got same error code, but car works fine accept engine light is on?