Hey everyone. I’m new to the club and I’ve been running into an issue with my 04 SC430. The CEL came on and it threw a code for the knock sensors. Replaced both sensors and the code back back again about a week later. I read somewhere that I should also change the wiring harness when I change the sensors. Is this true? If I do this and the problem continues what should I try next? Thanks!

 

Hey and welcome. Can you tell us exactly which "Codes" were thrown? You can also search the forum here using that code in the search and you might be surprised what pops up. Standing by.

Paul

 

It’s code PO325

 

Now go up to the top and select the search tool. Paste the code in and voila, you will get several from SC and other Lexus Model forums. Review them and see if anything helps. Im just telling you this because this particular code is unfamiliar to me personally but Im sure others will chime in soon if they can add to the conversation.

Paul

 

Google the code yielded this:

What repairs can fix the P0325 code?

1. Replacing the ECU.
2. Repairing or replacing the wiring harness.
3. Replacing a faulty knock sensor.
4. Repairing an electrical connection.

Good luck

 

"Replace the ECU."

Yea, I saw that. One of the searched post I saw even has a method to connect bank 1 and 2 together to the ECU. But unless he is comfortable with wiring, that could be a scary concept trying to figure that out. Its not hard. Just a real PITA.

Paul

 

I replaced the knock sensor wiring harness with a OEM one from Lexus. The problem was fixed for 3 days but then the CEL and the same code came back on again.. shoukd I try replacing the ecu? I’ve already spent too much money on knock sensors and the wiring harness.

 

Here is a ClubLexus SC430 specific search for that code
https://www.google.com/search?q=club...&bih=927&dpr=1

Did you have any other symptoms other than the check engine light? Loss of Gas Mileage or knocking when you floor it?

Do you have access to techstream? I believe you can get live data from your knock sensors when it is hooked up. If you don't get data, that would confirm a wiring issue or an ECU issue.

 

yes I get significantly low gas mileage and the car feels like it lost half its power. I also want to note that the CEL and the symptoms I mentioned go away for a few days then come back on, in. 3 day off one day on pattern.

 

You still only get 1/2 power?

Did u replace the sensors yourself or have someone do it for you? Did you think it was a pain in the butt and that you never want to do it again, or was it not so bad?

My gut feeling is that the wiring harness went bad. Engines get really hot and the harnesses sit right above it. However I heard removing the manifold was a pain in the butt.

You can try throwing $100 at the problem and replace the ECU with a used one. If it doesn't fix the problem, you can try to sell it and recoup your hundred dollars
https://www.ebay.com/sch/i.html?_fro...24700&_sacat=0

Then you can plunge in and replace the harness.

 

I already replaced the harness with a OEM one. The knock sensors were aftermarket and a mechanic installed them.

 

Great, that rules out the harnesses. See if you can get someone with techstream to try and get knock sensor data. If you get it then the ECU is probably good also and the aftermarket Knock Sensors are bad. If you don't get it, then the ECU is probably bad

 

Personally, after having issues with aftermarket sensors in general, I wouldn't try using any again. I would buy OEM from a Lexus dealer who gives at least a 25% discount.