Knock sensor code. cant clear it. bad knock sensor?

[aaronllewellyn]

1991 legacy ss,

the other day my hose going from my recirculating valve back into my intake somehow managed to disconnect,

It felt like I had no power, like there was just "no gas" either way I found the hose was off the next day, barely got it home.

I pull the check engine light codes and get

33 - Which is my known bad ABS speed sensor.

AND

22 - Knock sensor

Wow there's my problem, I assume the un-metered air getting into my intake caused me to run lean and detonate (mildly I may add since the engine is unharmed)

So I figure, I re-clamp the hose back on, the code will just "go away"

drive it down the road, it's BETTER, but will not go over 4~ psi of boost pressure, I checked the description of the code and it seems when it's on it will put me in "limp mode" retarding ignition and enacting an awful fuel map.

so yet again, I assume clearing the code will reset the sensor and cause the car to drive properly, I try clearing the code and no-matter what after two tries (the whole process) the knock sensor code will remain after "clearing" would this be an indication my knock sensor itself is bad? when engine is not running (has not been started after clearing) it still sends a knock sensor code...

[aaronllewellyn]

Bump, knock sensor replaced, check engine light off, but now I have only 5-6 psi reading on my boost gauge instead of 9.... doesnt really feel like the cars lost power so... maybe my gauge wire got kinked while I was messing about under the steering wheel

[robertpaige]

Possible. What gauge do you have? Does it read directly at 0 when the car is off?

[aaronllewellyn]

Possible. What gauge do you have? Does it read directly at 0 when the car is off?

It's actually acting like it's still in limp mode (it was when the knock sensor stopped working) I have no engine codes now, but it's acting like it's stuck in limp mode

how can I resolve this....

[aaronllewellyn]

Possible. What gauge do you have? Does it read directly at 0 when the car is off?

I can feel the power loss, it's "better" with the knock sensor in but still stuck at 5psi. wouldn't it stop being in limp mode when the check engine light is off... is it possible to be stuck in limp mode.

[aaronllewellyn]

Cleared the codes turned the key and BAM, there's the knock sensor code again, what the hell... I just replaced it...

at this point I imagine it's the knock sensor wire, at this point I'm officially sick of this car, finally get another transmission in it after not being able to drive it for months and it puts itself in limp mode over a knock sensor wire.

[Legacy777]

I would suggest checking the knock sensor wiring.

Code 33 is the vehicle speed sensor code and has nothing to do with the ABS. A bad or missing speed input to the ECU can cause issues. Does your speedometer work?

[aaronllewellyn]

I would suggest checking the knock sensor wiring.

Code 33 is the vehicle speed sensor code and has nothing to do with the ABS. A bad or missing speed input to the ECU can cause issues. Does your speedometer work?

speedo works (5mph off after changing to 4.11) although a front abs sensor is bad, the knock sensor code 22 is what's showing up every time, wish I could disable the limp mode so I could at least drive it to work.

[cj91legss]

The VSS Code 33 will also put you in limp mode. If the speedometer works, I'm wondering if there's an internal problem in the cluster.

[aaronllewellyn]

The VSS Code 33 will also put you in limp mode. If the speedometer works, I'm wondering if there's an internal problem in the cluster.

code 33 is due to a bad front ABS sensor ( I think I killed it pulling axles in and out ) it had the check engine on after my transmission install for a while, then the light went off, it didn't go into limp mode until my hose going from the recirculating valve to the intake popped off somehow, but now it will not go away, I was thinking maybe I have a bad MAF but noticed the code came on after clearing them before the engine had even been run again.

I also had a problem with my turbo burning harness wires, but I thought I resolved it with some re-locating and heat wrap, maybe the knock sensor wire got toasted, tomorrow I'll try to check the wire itself and see if it's getting to the ECU and go from there.

The speedo is 5mph off as well, I assumed because the gearing's been recently changed from 3.90 to 4.11

[cj91legss]

Is your ABS light on? If there's a fault with an ABS sensor, I believe the ABS light itself will be on. I don't think a fault in the ABS system will turn the check engine light on.

http://www.surrealmirage.com/subaru/eng ... l#resetecu

Now I could be completely wrong about this, but I don't think the ABS has anything to do with the VSS. I say I could be wrong because I have never had ABS, I had the pump on my 92, but never ran the electronics for the ABS at all.

Search the forum for the Jurisdiction ID pin on the ecu, I recall having issues resetting the ecu I had in my Turbo Legacy. It just wouldn't let me. I snipped the wire and put insulated connectors on it (male and female in case it didn't work so I could just plug it back in) and was able to clear codes and reset the ecu.

[aaronllewellyn]

Is your ABS light on? If there's a fault with an ABS sensor, I believe the ABS light itself will be on. I don't think a fault in the ABS system will turn the check engine light on.

http://www.surrealmirage.com/subaru/eng ... l#resetecu

Now I could be completely wrong about this, but I don't think the ABS has anything to do with the VSS. I say I could be wrong because I have never had ABS, I had the pump on my 92, but never ran the electronics for the ABS at all.

Search the forum for the Jurisdiction ID pin on the ecu, I recall having issues resetting the ecu I had in my Turbo Legacy. It just wouldn't let me. I snipped the wire and put insulated connectors on it (male and female in case it didn't work so I could just plug it back in) and was able to clear codes and reset the ecu.

The abs light is on for the Abs, and the vehicle speed code 33 is on because if the bad abs sensor or because of my changed gearing and my gauge cluster not being calibrated for 4.11 I assume? although it did not illuminate the CEL until the knock sensor went awry.

tomorrow I'm going to replace the knock sensor wire with a new one, I will use probably 18ga. wire, "unshielded" unless someone sees something horribly wrong with not using shielded wire.

[cj91legss]

I have 4.11 gears in my ss, the vss never came on for that. However I have never had the abs hooked up in my ss. My other ss has the abs light on all the time, but there is no check engine light.

I know this doesnt help your knock sensor code, but the vss code will likely put your car into limp mode.

Tonight you should pull the fuse 14 ecm/tcu and put it back in the morning and let the car idle for 10-15 minutes and see if the codes go away.

You should use shielded wire.

Sent from my SGH-T889 using Tapatalk

[Legacy777]

code 33 is due to a bad front ABS sensor...

I guarantee you code 33 is NOT related to the ABS sensor. The computers in these cars are stupid in comparison to modern day cars. The ABS and engine control unit are completely separate control units and there is not any wiring linking them together.

If you have a code 33 it is or was related to the speed sensor in the gauge cluster. If your speedometer works, then it was likely a bogus code. Following the instructions to clear the codes should clear it.

[aaronllewellyn]

I have 4.11 gears in my ss, the vss never came on for that. However I have never had the abs hooked up in my ss. My other ss has the abs light on all the time, but there is no check engine light.

I know this doesnt help your knock sensor code, but the vss code will likely put your car into limp mode.

Tonight you should pull the fuse 14 ecm/tcu and put it back in the morning and let the car idle for 10-15 minutes and see if the codes go away.

You should use shielded wire.

Sent from my SGH-T889 using Tapatalk

I'll get shielded wire from radio shack as others have said, did some reading on how the sensor works and realize shielded wire allows it to work properly.

[aaronllewellyn]

code 33 is due to a bad front ABS sensor...

I guarantee you code 33 is NOT related to the ABS sensor. The computers in these cars are stupid in comparison to modern day cars. The ABS and engine control unit are completely separate control units and there is not any wiring linking them together.

If you have a code 33 it is or was related to the speed sensor in the gauge cluster. If your speedometer works, then it was likely a bogus code. Following the instructions to clear the codes should clear it.

speedo is off by exactly 5mph, so you're going 55 it reads 60.

[cj91legss]

I replaced my cam, crank, knock, and iac with shielded wire on my old harness.

Sent from my SGH-T889 using Tapatalk

[cj91legss]

code 33 is due to a bad front ABS sensor...

I guarantee you code 33 is NOT related to the ABS sensor. The computers in these cars are stupid in comparison to modern day cars. The ABS and engine control unit are completely separate control units and there is not any wiring linking them together.

If you have a code 33 it is or was related to the speed sensor in the gauge cluster. If your speedometer works, then it was likely a bogus code. Following the instructions to clear the codes should clear it.

speedo is off by exactly 5mph, so you're going 55 it reads 60.

Thats not going to throw a code.

Sent from my SGH-T889 using Tapatalk

[James614]

The VSS code comes from an out of spec voltage reading from the sensor's circuit, it has nothing to do with how accurate the sensor or the signal is. The ECU has no way of knowing or caring how accurate it is.

[aaronllewellyn]

The VSS code comes from an out of spec voltage reading from the sensor's circuit, it has nothing to do with how accurate the sensor or the signal is. The ECU has no way of knowing or caring how accurate it is.

I'll be working on the Knock sensor tomorrow, I believe the reason it's grounding is because the side of my harness was burned near the turbo, burning the shielding, I shifted these wires when I heat wrapped them, now I'm convinced my wrappings could have grounded the wire by pressing the shielding into the signal wire.

I'll unwrap all my heat wrap (ugh) and check that wire I remember could have been exposed, hopefully it's the knock sensor wire I remember a slightly larger gauge wire being a little toasted... maybe the knock sensor wire.

[cj91legss]

Knock sensor wire is small and brittle.

Sent from my SGH-T889 using Tapatalk

[aaronllewellyn]

Knock sensor wire is small and brittle.

Sent from my SGH-T889 using Tapatalk

hmmm, then I guess I'll try to check the continuity, if it's unbroken it will read Ohms on the multi-meter correct?

going from the knock sensor connector to the signal pin on the ECU.

[cj91legss]

It should read 0 ohms

Sent from my SGH-T889 using Tapatalk

[aaronllewellyn]

It should read 0 ohms

Sent from my SGH-T889 using Tapatalk

got it,

assuming I can easily find the signal and ground/shield wires on the ECU B56.5 for signal and B56.4 for the shield as it seems

so I'll be cutting the wire as far back from the knock sensor connector as safely possible, peeling the shielding up from both ends, crimping the signal wires together then connecting the shield wires together, then repeating the same process on the other end with the signal and shield wires.

just found a mono audio cord that's shielded, and a small gauge, I'll most likely use it.

stop me if this is a bed method.

[aaronllewellyn]

So far I have cut the connector, stripped the connector wire as well as the audio cable tube crimped the signal and grounds to each other, plugged it back into the knock sensor and run the wire through the firewall.

checked my continuity and made sure my connections were good.

I cant seem to remove the connector B56... I'll keep working on it, there's way too many wires under here.


EDIT: plug is out, It seems these wires have been replaced before, it's shoddily electrical taped together! not even crimped! either way the Black is ground and white is signal? correct.