1994 volvo 850 turbo wagon - Knock, Maf Sensor Codes

southofmotown · Post by **southofmotown** » 28 Aug 2015, 18:16

I have a check engine light that says it is either my knock airflow sensor or my mass airflow sensor. The vehicle drives fine for me, but I would like to get the check engine light turned off. What is my first step in resolving this issue? Thanks.

Post by **abscate** » 28 Aug 2015, 20:01

The first step is to read the actual code, but as luck would have it, it's not the knock sensor. It may not be the MAF, but I'll bet Matts Volvo it's not the knock sensor

southofmotown · Post by **southofmotown** » 28 Aug 2015, 20:06

Well I suppose the easiest place to start would be to clean the MAF sensor.

Post by **RussB** » 28 Aug 2015, 21:40

No, read the actual codes and post them. What is a knock airflow sensor?

southofmotown · Post by **southofmotown** » 28 Aug 2015, 21:50

Okay I will have to go back and get the actual codes. Heard of a MAF sensor, but I had never heard of a knock sensor either. That's why I'm trying to find answers in the forums.

Post by **RussB** » 29 Aug 2015, 05:12

southofmotown wrote:I have a check engine light that says it is either my knock airflow sensor or my mass airflow sensor. The vehicle drives fine for me, but I would like to get the check engine light turned off. What is my first step in resolving this issue? Thanks.

The bold text is key here. If the MAF was faulty, the car would barely drive.

Didn't you recently replace the PCV system? I mentioned it in another reply, but if you could consolidate your threads, or at least provide links to them we could follow what you have already done and help with the puzzle that is your '94 T5

Post by **abscate** » 29 Aug 2015, 05:21

If you have recently have done PCV, you probably have a vacuum leak from a hose

southofmotown · Post by **southofmotown** » 29 Aug 2015, 06:31

Didn't you recently replace the PCV system? I mentioned it in another reply, but if you could consolidate your threads, or at least provide links to them we could follow what you have already done and help with the puzzle that is your '94 T5

Yes I did recently replace the PCV system. I'm not sure how to consolidate threads. I thought it would be more helpful to keep them each on topic, rather than being all across the board.

Post by **RussB** » 29 Aug 2015, 06:57

southofmotown wrote:
Didn't you recently replace the PCV system? I mentioned it in another reply, but if you could consolidate your threads, or at least provide links to them we could follow what you have already done and help with the puzzle that is your '94 T5
Yes I did recently replace the PCV system. I'm not sure how to consolidate threads. I thought it would be more helpful to keep them each on topic, rather than being all across the board.

But how can we follow? I certainly don't remember what you've posted before, and it is all relevant.

Did you disconnect a knock sensor while doing the PCV for more clearance? Of damage the wiring? I seem to recall that some 850's had issues with the factory knock sensor wiring harness???

southofmotown · Post by **southofmotown** » 29 Aug 2015, 08:28

I believe the knock sensor is down near the oil trap, right? I didn't touch it and I don't remember seeing any broken wires. Does it have an electrical connector where it plugs in? I should tell you that this was the code I got BEFORE servicing the PCV. Since the check engine light is still on, I'm only assuming it's the same code.