Knock Sensor Harness, 1994 Turbo 850

rsmigel · Post by **rsmigel** » 08 Jun 2020, 11:25

Hi All,

Just picked up two consecutive P0326 knock sensor codes on my '94 850 Turbo Wagon within the last week. Car has 190K miles and I've owned it since 1995. The sensors are original and have never outputted this code.

As the cause may be connector related, is it possible to disconnect, clean and reconnect the connector w/o pulling the intake manifold? Or is the connector inaccessible? I replaced the EGR systema few years back and know it's a pretty big job that I'd like to avoid.

Post by **rguzz** » 08 Jun 2020, 12:24

Lot's of info on this subject available by search, I asked a similar question a couple of weeks ago. Ultimately I pulled a battery cable, let it sit 2 hours, reconnected, CEL immediately appeared, off it went with my scan tool not back yet. Any other codes, or unusual behavior? If not try a hard reset before you get in to breaking a bunch of stuff down. As we know, knock sensors themselves rarely go bad. This code will pop up if a sensor becomes annoyed, you might get lucky as I did. Simple enough to do, anyway. There is always this, which really answers your question I think: viewtopic.php?f=1&t=77262

rsmigel · Post by **rsmigel** » 09 Jun 2020, 13:49

Nope. No other codes and the car runs well at all RPMs and under all loads. I'm getting 25-26 mpg, country driving, with the light on. Gas is fresh 89 octane but the light went on with the previous tank. Six months back I adjusted the turbo actuator 1.5 turns shorter to engage the turbo earlier but no lights until the last week. I'll try the hard reset by disconnecting the battery cable next.

Post by **rguzz** » 09 Jun 2020, 19:35

I rarely use less than 91 octane gas. Especially after my valve rebuild. If your code comes back instantaneously after a hard reset, use your scan tool to erase it.

rsmigel · Post by **rsmigel** » 12 Jun 2020, 06:05

I did a hard reset and the light came back on after 15 minutes of driving. So now I will buy a new sensor assembly.

redbeak1 · Post by **redbeak1** » 19 Jul 2020, 21:57

rsmigel wrote: ↑12 Jun 2020, 06:05 I did a hard reset and the light came back on after 15 minutes of driving. So now I will buy a new sensor assembly.

Did you ever figure out your problem? I just pulled the manifold off and see the connectors are all green inside. Cleaned it up with CRC electronic cleaner. I also bought the knock sensor upgrade from IPD which eliminates the two connectors, but requires splicing into the wiring harness. I also had a Knock sensor code that wouldn't go away.

rsmigel · Post by **rsmigel** » 09 Nov 2021, 04:51

redbeak1 wrote: ↑19 Jul 2020, 21:57
rsmigel wrote: ↑12 Jun 2020, 06:05 I did a hard reset and the light came back on after 15 minutes of driving. So now I will buy a new sensor assembly.
Did you ever figure out your problem? I just pulled the manifold off and see the connectors are all green inside. Cleaned it up with CRC electronic cleaner. I also bought the knock sensor upgrade from IPD which eliminates the two connectors, but requires splicing into the wiring harness. I also had a Knock sensor code that wouldn't go away.

One year plus I get the knock sensor error code re-appear every few weeks to every few months. Over the last twelve months I’ve reset the code ~8 times. The car runs fine and it’s easy to reset the code. I’ll change out the sensors should I ever have a need to pull the intake manifold for another reason.

Post by **abscate** » 11 Nov 2021, 04:18

I bet if you return the turbo to spec you won’t see those codes.

The boost on Volvos from -1998 is open loop, so you can easily be overboosting. Knock sensors hear knock well before you do