P0325 Chevy Cruze

Does the vehicle perchance have a lot of knock sensor activity on a high RPM deceleration? eg: 4000 rpm coast down in 1st gear. If so it is likely you're dealing with an internal engine failure and not a knock sensor problem.

Not only is there no knock activity anywhere, this code comes back immediately at key-on. You don't even have to run the engine. 2 key cycles and it's there.

This is exactly what I suspected on my 07 Toyota Sienna, there is an audible knock and I'm sure that will throw knock codes which come on and off intermittently since the crankshaft is most likely worn at the bearings. I would monitor the signals with an oscilloscope and compare with a known good that someone can probably help on getting or already have.

I had the same car, engine and code. It felt in like it was retarding the timing at low rpm (it was a standard so it was easier to feel). It turned out it was the bolts that held the upper timing chain guide on had come loose and the rattle was being picked up by the knock sensor. I didn't hear any obvious noise. The bolts seemed to be stretched and didn't feel right tightening them up so I…

Load test all PCM powers and grounds. Any chance the new knock sensor is junk/aftermarket? I believe about 1 volt on the ground is ok. Many manufactures will elevate the ground voltage on 02 sensors, knock sensors, digital wheel speed sensors etc to keep the signal clean (along with other reasons im sure). Turn the key on and tap the block around the area of the knock sensor while watching the…

Power and ground are good. Knock sensor is brand new ACDelco, as were the two that preceded it. I talked in this last one by hand myself to 14 foot pounds, which is one under spec. To reiterate - this code happens at key on. It is not a knock event. The engine is not running. It's a circuit code, and it throws it as soon as you cycle the key twice. Once again, all of the wiring has been…

Sounds as if the wires are crossed but you said you verified this. Also, from service info: “The ECM receives the knock sensor signal through a signal circuit and a low reference circuit. The ECM learns a minimum knock sensor noise level at idle and uses calibrated values for the rest of the RPM range." So, this makes me believe that you have to run the car to learn that min value at idle…

3 ACDelco sensors in a row. Wires verified for pin to pin color.

I found the table for possible causes for setting this DTC and you will get this P0325 if the low ref is shorted to power which in this case appears to be case since you're reading 1.2V (partial short). The only thing left for you is to cut the low ref wire at the PCM and run a jumper to the spliced KS connector, that wire has to be partially shorted to positive within the harness, an ohm test…

As noted in the original post - I cut BOTH wires and ran all new wiring directly from the sensor to the PCM.

Did you cut both ends, meaning, completely eliminated both wires or just spliced from the PCM? I will try to get a knock sensor signal from both wires using an oscilloscope tomorrow and I will share it with you. You've done everything but I still believe you may have missed something. Cant really blame the PCM since it has been replaced.

Is the engine block close to 0V as compared to the negative battery post?

Yes. 6 ohms. Less than .1v

The computer runs tests on both wires that might look like this: diag​.​net/file/f2t7zdatu… ​ You need a scope, not PowerProbe, for this task! Though checking resistance of the sensor could be useful too.

I can scope it - but are you suggesting that the low ref line is not ground but a 180° phased signal? GM disagrees. You are showing a waveform for low ref that oscillates from 1.x to 2.x. GM says this should be a flat, 0v ground.

I think Dmitry is showing a very brief power-on self test (2500 ms---1/4 second), followed perhaps by a second circuit test. After that, as you say Jeff, it should return to a something akin to ground. Its possible all "low references" aren't common to each other inside the PCM so when you borrowed one from a different circuit this was the reason for a change to the "low signal" code. I've…

So 1,4 L spec is 0v ? …I thought was worked like Dmitriy says KOEO 1-2v Bk/Yl & 2-4v Violet/Gray … P0325 usually the sensor on Cruze but a 4th bad peizo hard to believe . P0327 pops on the Chevy KS system that's 2-5v KOEO each terminal in connector ,not sure what your ground switching did Id have to think top hard about that or if related .

Doesn’t GM’s SI say this: diag​.​net/file/f250lyv74… ​

It it did, this would pass - but it throws the p0325 anyway. But, no - the SI says this: diag​.​net/file/f1nzqwtdr… ​

Perhaps the SI is not correct in multiple respects (its happened before...). For starters (from SI) this code shouldn't be setting at key-up: Conditions for Running the DTC P0325 •Engine speed is between 580–8 500 RPM. •The ECT is greater than −40°C (−40°F). •The IAT is greater than −40°C (−40°F). •This DTC runs continuously within the enabling conditions. •The DTCs run continuously when the…

Something doesn't match up in my mind....when you made your measurements initially and failed the 10 ohm measurement, you say you had over a volt on the low ref wire.....but the test conditions are supposed to be done with the ignition off and 2 minutes of power down. Do you really have this voltage under the referenced test conditions? Any chance other codes are setting? like P06B6? When the…

You both have incorrect service information. Here is what SI states. I can almost promise you this has an open/high resistance. Check terminal tension at ECM. This code sets for an open only and is likely failing the ECM self test as Dmitriy says. I have said this before but I will say it again, when servicing GM vehicles, you are doing yourself a disservice not using GM factory service…

Well, it's definitely not an open and it's definitely checking it at key-on. Once again - all of the wiring from the PCM connector onward has been completely replaced all the way to the knock sensor, including the pigtail for the sensor itself with dealer parts. There's no overlaid wiring. It was completely replaced and there is good continuity from pin-to-pin from the PCM header to the knock…

I am just trying to help you… I am gonna lay it out as it do to my customers. It is me and you vs the car. Not me vs you vs the car. Logically this doesn’t make sense. I can almost guarantee you are missing something (and it is an open/high resistance) as you have had 2 pcms, wiring replaced, a sensor pigtail, and almost countless sensors. Did you replace the knock sensor (2) pins at the pcm…

Well said William. You are correct that the GM SI chart, (the one with your circled areas), is quite similar in identifix but different. Not sure how this happens. It does have one similarity that states the condition for running OR setting the DTC is a running vehicle....Any thoughts on why Jeff might be getting this code with key on only (2 cycles)?

Yea I sure do. It is a type B DTC which in GM world means it is a 2 trip fault. So the logic has to see the fault 2 separate times on two separate ignition cycles of the key.

What Kerry is asking is about the running vehicle condition: diag​.​net/file/fnjutt3vk… ​ At this point, after seeing the waveform from Jose Luis, I think all SIs are wrong!

Gotcha yea I misunderstood I believe you are correct. I believe the ECM conducts this test immediately with the key on, but I would have to talk to TAC to verify. I am not so concerned with when the test is run as why is it failing. I believe the test conditions are correct for the complete test cause the logic wants to adjust for signal noise while the engine is running . I believe it fails…

AC Delco is just a standalone parts supplier, and has been for decades. It is not a part of GM so parts from them are not OEM stuff, but OES. Not to say that your three sensors are all bad, but it may be a calibration issue. Try a sensor from the dealer and not from the parts houses. You've basically covered all the rest of the possibilities. There are also tons of issues with coolant…

Parts came from the Chevy dealer.

There isn’t a difference in knock sensor between manual and auto?

Check the waveform, the sequence goes, Key on where you see the first voltage change for both wires, I put comments on them so you know which is the sensor wire and low ref wire. Then, it kind of quiets and then I starts the car and you see more noise. There is no real change in voltage as you can see. I did not notice any change in nominal voltage. This is from a 2013 Chevrolet Tahoe 5.3L LT…

Nice! 2013 seems to use the same bias voltage for both wires. 2014+ may be using different biases? But what's fun to look at is the A-B math channel: diag​.​net/file/f2t8x1jgb… ​

It seemed odd to me too, I checked again in case I may have crossed the wire but no, it is the same signal coming from the sensor for both wires.

That 5.3 system works Exactly the same as this Cruze. I checked. The logic is looking voltage to be the same on both wires as the sensor itself completes the circuit. That is how the ECM knows the circuit is whole. It is a piezo sensor so it creates it’s own voltages for the knock frequency, the ECM only uses the bias voltage for self testing. Hench why it is a two wire knock sensor and not a 1…

Went through the same thing earlier this year, a factory knock sensor fixed it. If it was a aftermarket sensor replace it with a factory sensor. Have you pulled the covers off of the connector on the pcm to check for water intrusion in the connector itself.

Can I ask you - did you read any of this thread before you responded? Did you even read the response directly above yours?

My fault for any misunderstanding, you say you have completely replaced the wiring from the pcm to the knock sensor, did this include new terminals in the pcm connector itself?

There should only be three possible faults pcm, wiring or sensor. Over the years we have had a couple of vehicles that the factory parts manual gave the wrong part number, a Nissan that had 2 possible front impact sensors that was not listed in the parts manual and a jeep that used different corner sonar sensors than the middle sensors. You might call a different dealer and check for a possible…

Wow, nice work man. Thats absolutely disgusting the lack of quality.

This is an older post I recall and without rehashing ,that's all it could have been again and again …..5 might be the record .

Yep, that matches my record for bad PCMs as well…I had five in a row with the same code myself.