Hello evo m ers.
I was hoping someone could give me some tips on troubleshooting a CEL I keep posting after a track day at Fontana speedway. Initially I just assumed it was like so many other knock sensor error codes in that something in the exhaust has come lose or rattles, which sets off the sensor. However I haven't found anything. Its all solid.

I have read tons of knock sensor posts and the only conclusion I have is that its mostly not the sensor but something setting it off.

If this post is in the wrong forum to get the most input I won't be offended if a mod moves it. I had trouble deciding where I would get the most useful input.

Here is the scenario:
Car ran fine all day, as always, and in the end session sudden drop in power, likely pulled timing, and a CEL. My impression was that it was accompanied by more exhaust noise. Based on that, and what I have read over the years, my DP or straight pipe got lose, or an 02 sensor blew out. I called it a day. At home I cleared the CEL and it comes back as soon as the car is warm, no load needed. No rattles, no lose exhaust, nothing I can find. No driveline noise. It was a hot day, and at 140mph on the straight not surprising that I threw a CEL.

Does anyone have any experience with what I should troubleshoot to find the cause? P0325 states circuit. Is there a way to check the sensor is good or not. Like a resistance test. Or is the info on a continuity test between the ECU and the connector?
This is the kind of in depth troubleshooting I had to do for an O2 wire harness issue years ago. (I got lots of help here to solve that

I am open to any ideas, because I have spent a couple of days getting nowhere.

Thanks
Mike

 

Bump,

Man I am having a tough time getting folks interested in this issue. I admit its not a glorious, but help me out.

I have since the OP replaced the knock sensor, and confirmed that the white wire continuity to the ECU is good. Pin91 to the plug, form there a new sensor. I get the same P0325, knock sensor circuit error.

Do you guys have any guesses or paths to troubleshoot. I have read literally every post that has P0325 in it, and many more knock sensor posts, and its mostly just lists.

M

 

Resolved by carefully following the FSM diagnostics steps for troubleshooting the sensor. Of course I did that correctly after replacing the sensor unnecessarily. The key was to check for a slight short circuit of the white wire, 91. This wire in the harness must have began to get a couple of electrons jumping to it from the grounded and shielded green wire it sits within. A sensitive enough setting on the ohm meter eventually showed that this wire was getting grounded ever so slightly.

For now i ungrounded the shielding wire, and the knock sensor seems to operate appropriately. However, this is likely not a good long term solution.

The take away here for folks is that the P0325 was exactly what it states. A faulty circuit. In my case the knock sensor's current wire was being grounded due to a likely damage somewhere in the harness. Testing Continuity isn't thorough enough, you need to check that your lead wires aren't being grounded to cause the faults.