Check light blues

Squeaky · Post by **Squeaky** » 01 Aug 2006, 22:32

Ever since I purchased my "experienced - 300,000 km +" 1994 850 Turbo wagon a year and a half ago, I have been plagued with engine check light problems. I have replaced oxygen sensors and knock sensors and yet it still continues to come on. After "X" number of starts, it usually goes off by itself, but in this last cycle it has stayed on for several weeks.

It has always started without hesitation, run smooth as silk, had the typical awesome turbo punch, and the gas mileage has been very good and very consistent, light off or on.

My local dealer cannot explain, and all but agrees that I may have spent all that money on sensors unnecessarily.

Can anyone shed any light on this? Is there any possibility that I'm doing damage by running it with the light on?

How about disconnecting the **@@###!! thing altogether - aside from the obvious fact that if there is a real problem, I won't know, I'm quite serious about the disconnect!

Squeaky

White850Turbo · Post by **White850Turbo** » 02 Aug 2006, 06:12

What codes are you actually getting?

gtg737m · Post by **gtg737m** » 02 Aug 2006, 07:49

I have a 1994 850 turbo wagon and I have exactly the same problem. I've changed the front oxygen sensor, the MAF sensor, the knock sensors(twice), and the check engine light still is on. I even changed the ECM and it didn't make a difference. The code that I always get even though it has new knock sensors is for faulty signal from the knock sensors. The Volvo dealer suggested changing the entire wire harness of the engine but I'm still thinking about doing that, it's like $2,000. Tomorrow I'm going to have the waste gate of the turbo changed now that I think I have a sticky wastegate which makes my car boost more than normal. If this doesn't fix the CEL problem then I'll consider changing the wire harness after getting a second opinion from another Volvo shop even though the dealer should know this cars better than everyone else. Good luck with your CEL problem. I'll keep you posted about how my car is doing after changing the parts I mentioned above.

Squeaky · Post by **Squeaky** » 02 Aug 2006, 23:17

The code is always the same - knock sensor.

I've changed the knock sensor twice and installed an upgraded wiring harness for it.

I dropped by the local dealer today to have the codes read (what else - knock sensor) and the light shut off. They are going to contact Volvo to see if anyone there has any ideas (which they promised to do before - about three months ago).

What grade of gasoline do you burn in your 850 turbo gtg?

Thanks to you both for your input.

Post by **MadeInJapan** » 02 Aug 2006, 23:20

Did you turn your knock sensors to 3:00 and 6:00? Proper positioning will make a difference in how they read and send codes.

gtg737m · Post by **gtg737m** » 03 Aug 2006, 03:52

The dealer changed them so I guess they applied the proper torque and they put them in the correct positon. Today I'm taking it to the dealer to change the wastegate actuator, I'm crossing my fingers hoping this is the problem. I'll keep you posted.

gtg737m · Post by **gtg737m** » 03 Aug 2006, 07:19

I always put the best gasoline in my car. I haven't sold the car yet now that it has turned in to a challenge to get the problem of my car fixed, plus I'm a big fan of the 850 Turbo wagons. According to the dealer, they contacted the Volvo headquarters in New Jersey and what they suggested was checking the connections from the knock sensors to the ECM. Apparently everything looks good but what the Volvo mechanic is saying now is that that connection might be disturbed as the engine gets hot and runs for a while. That's why they suggest changing the wireharness but they cannot give me any warranties about that job. Any luck with your car?

Squeaky · Post by **Squeaky** » 05 Aug 2006, 23:30

Three days later and the check engine light is back on - no surprise, but it's driving me to distraction.

As I mentioned, the dealer is supposidly contacting Volvo for some advice.

From all the check engine light threads regarding the 850 Turbo model on this site, I guess I'm not the only one, but I'm quite surprised that no one, or their mechanic, has coaxed a meaningful answer from Volvo.

Squeaky

Post by **MadeInJapan** » 05 Aug 2006, 23:36

Could be as simple as bad wiring. Hope they figure it out for you soon. I know how frustrating these things can be.

gtg737m · Post by **gtg737m** » 08 Aug 2006, 10:06

I had the dealer change the waste gate actutator thinking that the waste gate was sticking causing the car to over boost but the CEL came on again with the knock sensors code. I went to an indepedent Volvo shop this morning and they told me that several years ago they had an 850 that was doing a similar thing but they found out that the engine was over heating causing the pistons to sound louder than they should. The loud noise of the pistons would activate a code for the knock sensors. The mechanic at that place told me that my car is not over heating and that I should just ignore the CEL or just take the bulb out. He told me that he could put one of his mechanics to work all day in my car and he wouldn't find a way to fix this problem but he would still have to charge me $80 per hour for labor. For now I'm not going to spend more money on this problem but I'll still continue doing research and keep everyone updated if I find out something new. I'm not going to go with what the dealer is telling me which is to change the entire wire harness of the engine, too much money and they don't gave me any warranty if the CEL comes on again. Good luck fixing your car and if you find something out please let everyone know.