Code P0325 keeps coming up

Welcome to 2CarPros.

The knock sensor is responsible for fine tuning ignition timing. If you are not hearing any valve tapping or engine noise, you should be okay to drive it, but if you do hear engine noise, I wouldn't want to drive it. It could cause other damage.

Here is a link that explains how one works:

https://www.2carpros.com/articles/how-a-knock-sensor-works

As far as the problem, if the sensor was replaced, chances are there is a short in the wiring or a bad connection. I will provide the diagnostics for the issue, but it will require some special tooling. The basic testing equipment I will provide links explaining how to use them.

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Here are the directions. All attached pics correlate with these directions.

Troubleshooting
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection P Code Charts P0325 Troubleshooting
TROUBLESHOOTING
CIRCUIT DESCRIPTION
Each of knock sensor is fitted to the right bank and left bank of the cylinder block to detect engine knocking. This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.

picture 1

DETECTING CONDITION
If the ECM detects the above diagnosis conditions, it operates the fail-safe function in which the corrective retard angle value is set to the maximum value.

picture 2

WIRING DIAGRAM

Step 1
picture 3

Step 2
picture 4

Step 3
picture 5

INSPECTION PROCEDURE

HINT:
- DTC P0325 is for the right bank knock sensor circuit.
- Read freeze frame data using LEXUS hand-held tester or OBD II scan tool. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.

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Here are a few links that you may find helpful:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

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Let me know if this helps.

Take care,
Joe

Did you replace both knock sensors? Maybe the wrong was replaced. Also if the replacement knock sensor was dropped accidentally then it would make it no good? What brand sensor did they put on as well? There are certain brands that are just junk. Let us know please.

Welcome back:

The brand is good, but were both replaced? Also, I never heard of splicing wiring to get rid of a code. Honestly, I wouldn't do it.

Let us know.

Joe

Welcome back:
I agree. If one was broken, there could be others. I will watch for your reply.

Take care,
Joe

Welcome back:

I'm in PA and can tell you I know when codes were reset. When doing an emissions inspection, the first thing I do is check to see if all monitored systems indicate complete. I will try to explain. When you clear codes, you basically erase everything. Then, you need to complete drive cycles for the component monitors to reset. If they are not reset, the scanner or emissions machine will reject it. Now, here is the catch 22. By the time everything resets and it is ready for the test, the check engine light will return indicating the problem is still there. Once the specific monitored system resets that is turning the light on, again the light will return.

I hope that makes sense. Sometimes the easiest things to explain see the most difficult.

Let me know if that helps and if you have other questions.

Take care,
Joe

Welcome back, Sam.

Honestly, I don't know of anyone in that area. I'm about an hour outside of Pittsburgh. As far as the issue, if this doesn't fix it, it could be related to the PCM. However, lets not think of that until we see if the problem is resolved. I will keep my fingers crossed.

Take care and I will watch for your reply on Monday.

Joe

Sam:
The reading indicates a lean mixture which usually isn't the oxygen sensor. The tech that watched how the vehicle was responding should be able to see how the o2 sensor is responding. Most times, there is an engine vacuum leak or even an exhaust manifold leak allowing unmetered air to get into the bank one system. Is it possible for you to have him scan the sensor to see if it is responding before you get a sensor?

Also, most times a sensor goes bad, the computer over compensates fuel mixture which would cause the opposite, a rich mixture. Before you purchase a sensor, see if you can have that done and let me know the results.

Okay, I'm going to get a bit technical so you know exactly what to ask for if you take it in. If there is something I say you don't understand, let me know.

Anytime there is a driveability issue, the first things to check are short-term fuel trim (STFT) and long-term fuel trim (LTFT). Fuel trim is an extremely important and a key diagnostic parameter which is helpful in many ways. It tells the tech what the computer is doing to control fuel delivery. STFT and LTFT are shown as a percentage. In a perfect world, you want the range being within 5% of 0. The 5% can be positive or negative, but that is normal. When it exceeds that, then questions come up. Positive fuel trim percentages indicate that PCM is adding fuel to the fuel mixture to compensate for a lean condition. Negative fuel trim indicates the PCM is trying to lean the fuel mixture to compensate for a rich condition. With that in mind, you should see a negative STFT beyond 5%.

Now, If I know what the SHFT and LTFT are, that will help me to determine the next issue.

Now for the O2 sensor. Testing O2 sensors is simple. The sensor needs to exceed.8 volt and drop below.2 volt. The change from low to high and opposite should be quick. Most times, a good snap throttle test will verify the sensor’s ability to achieve the.8 and.2 voltage limits. If the sensor doesn't react in that manner, it most likely is bad. Also, the high output should be when the fuel mixture is richest (when you snap the throttle). Once the throttle is released, it should snap back to the low voltage.

If the sensor seems non responsive, confirm there are no wiring issues and if not, replace it. Also, if it remains at a high voltage reading, create an engine vacuum leak to see if that changes how it responds. If it is showing lean and doesn't change, you can actually use propane to create a rich mixture, but I don't want you doing that.

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Why did I ask for the fuel trims and to see how the sensor is reacting? Between the two, I will be able to tell if the computer is doing what it needs to do and if the sensor is actually faulty. I'm hope you understand this. I'm trying to focus on what is showing as the problem now and to determine if it is the sensor or not. I know what another $150.00 is like. Especially when it gets spent unnecessarily.

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Please feel free to let me know if you have questions or need clarification. Also, let me know what you decide.

Take care,
Joe

Welcome back:

I didn't see a prior post. Honestly, did the exhaust repair shop check the exhaust manifold for leaks? In my last post, I indicated a vacuum or even an exhaust leak. Now, however, it seems there are new problems.

Since one of the Air/Fuel Ratio sensors was replaced and now they are both showing up, the first thing I would check is what voltage is being indicated from the AFR sensors. Using a live data scanner, you need to check for output voltage from the sensors. With the engine warmed up, the voltage should be between 2.8v and 3.8v. If it goes above that or below, it will set the codes you have.

These codes weren't present before, correct? If they weren't, check the connection to both sensors. Make sure nothing is melted as far as wiring.

Let me know.
Joe

Welcome back:

I too will keep my fingers crossed. As far as the PCM, they do go bad. However, most times it is a wiring issue after the PCM or a bad connection at the PCM due to corrosion or a damaged wire. Just based on the sensor's location, wiring could be an issue due to heat. I attached a pic of sensor location in case you weren't sure where it is located.

Let me know what is found.

Take care,
Joe

Welcome back:

Wow, I'm not sure what to tell you. You may be better off at this point to take it to a dealer.

What I have done is provide the diagnostic instructions in pic 1. It may help you or the person you are taking it to. The second picture shows the plug connector to the sensor.

Let me know if this helps at all.

Joe

You could still have a defective part. Sometimes going OEM is better. Explain to the dealership you have already replaced all those parts and see what they tell you.