fdmt

First off I am a newbie and have been searching the forum and a lot of great info on here! Now my problem. 2000 Lexus ES300 3.0. Same old knock sensor codes that I have read about with limp in no OD. I have replaced knock sensors and wire harness, checked wiring harness from ec1 to ECM and also bypassed harness and replaced ECM with another ECM with immobilizer with fobs and still get the 2 codes. I have the all data DIY membership and have gone through the checks and have hit a road block. Am I missing something? I didn't have torque specs when putting in knock sensors but made sure they were tight but not overtightened. I did purchase them off the internet but I have never had problems before with other items not working. When clearing code and leaving scan tool hooked up I only get p 0325 and not p 0330 but if I unhook scan tool I get both which really is weird. Car runs great and no other codes and it has 274500 for miles. I looked at wiring diagram to see if maybe a ground but all data wasn't showing anything separate for that circuit so I figure it can't be one tied to another circuit or I would be throwing more codes. Thanks in advance for reading and any help you may have

LeX2K

What brand of knock sensor did you install?

fdmt

Don't know the brand but not OE. Didn't buy cheapest online but not the most $$$ either.

LeX2K

Might not be your problem, but many people have reported issues when using aftermarket knock sensors, especially on the generation 3 ES. To take the guess work out of things it would be best to get a hold of an oscilloscope and runs the tests as per the service manual.

fdmt

That was the only thing I didn't do as did not have one. Sad thing is I use to have a old engine analyzer with a scope on but got rid of last summer as I got sick of it taking up space.

LeX2K

Seeing you have even gone to the extent of replacing the ECU and you have the same problem, then throwing more parts (not to mention the work involved) at the problem doesn't seem like a good idea. But I can't stress this enough, these engines do not like aftermarket knock sensors.

PuReChaos

I have to side with Lexus2000. Replacing the ECM is the very last thing I would try and consider being the problem. My bet is its the aftermarket knock sensors. You've replaced the ECM and the wiring harness which are both the least likely to be the fault. an oscilloscope is definitely the direction I would head in. My guess is that these aftermarket sensors aren't sending an appropriate signal, not to say they aren't working at all, but I know some cheaper aftermarket sensors will send a signal too infrequently which will cause the ECM to think the sensor isn't functioning properly.

fdmt

Thanks for the input. I am going to try a couple of new sensors OE this time.

Mythotical

I played hell with mine too so finally I built a bracket on the side of the head, singled up the harness and mounted a used but known good KS to the side of the head and poof problem gone! I think I even get better performance now too. Good luck!

zapoteka8

could you please be more specific and show diagram/picture?
how do u mount the good KS to the side of the head?
thank u

DRACO A5OG

Take a closer look at the male side of the harness going into the ECU. if Knock sensors and Harness are new it should work if not for a short time at least.

Also your new harness did it "click" in? I found aftermarket ones are bit thicker and you need to force them into get a full contact.

But I would carefully look at the harness to the ECU.

I swapped my Sensors and new aftermarket harness and got the P3025, later I found the ECU side was compromised. Went to Pick a Part and found a decent ECU side harness and spliced it right in. No more P3025.

mugencivic

i'm also have the same issue. i'm debating whether to get the most expensive KS on rock auto, which is $110.00, or just cough up the $250.00 for the denso at the dealer :/

DRACO A5OG

I really do not think it is your sensors but the Harness only. I bet if you start the repair the connector will fall apart in your hands.

Basic resistance test will show those sensors are still good, not the best test but hate for you to spend all tat time and money for nothing.

If you do decide on the sensors, you need a new bypass hose as well. Go dealer on this, a perfect no guess fit. You do not want a leak there. A bug PITA.

TomES300

I'm having a similar problem with my 2000 ES-300 with the P0325/P0330 codes coming up. Usually the codes do not trigger until at least 30+ minutes of driving. Sometimes it's one code or the other, but most of the time both come up together. I replaced both knock sensors (aftermarket) + the wiring harness (“genuine”)connecting them almost a year ago; problem remained. I learned to keep a cheap ODB reader/resetter handy as I drove. Recently I replace the ECU to see if that would fix it; problem still remains. I’m not really a mechanic, and other than the fact that it won’t go into OD with the codes active I couldn’t care less about the check engine light. Any thoughts on what it might be, or a cheap alternative to “bypass” it (i.e. – spoof the ECU)?

DRACO A5OG

Take a closer look at the ecu side of the harness you replaced. If compromised, it will give a false reading.

Also make sure the connector is fully seated.