JazzyQuinn

I have a 1999 es300 that sometimes wont shift into overdrive. It keeps throwing me codes p0325 and p0330 for the knock sensors bank 1 and 2 despite all my efforts to eliminate the problem. Less than 1000 miles ago both knock sensors were replaced as well as the spark plugs, timing belt, and 02 sensor. All my fluids have been changed and are at the right level, yet my problem still persists. I took my car to a mechanic who scanned my car and found codes 325 and 330. He checked both knock sensors and got signals but one was was slightly erratic. He didn't that that should be giving me the problems I was experiencing so he cleared the codes,

The following week the CEL/TRAC OFF lights turned off and on every other day, and the problem came and went randomly. I drove it for 3 hours one day and it started shifting very sloppy and the rpms were really high. The lights have been on steady ever since. Yesterday I bought a obd2 code reader to find both codes 325 and 330 had returned. I cleared the codes and was able to drive the car hard with no problems, It accelerated quick, shifted great, and rpms were normal. After about 10 miles the lights are back on showing p0325 and the problem has returned, can anyone shed some light?

Mythotical

I have seen one of two things cause this. Either one of the knock sensors has come loose or the knock sensor harness is bad. I have moved one knock sensor to the end of the front head and jumped the harness to a single knock sensor and the knock sensor came loose in the bracket and gave me the same intermittent problem you have every 10 miles or so. I ended up putting a nut on mine as the bracket I made is only 1/4 thick aluminum. You will have to either tear it apart to fix and be sure to replace the harness too, or buy one knock sensor and a harness and do what I did.

P.S. Moving the knock sensor did improve performance a little too.

LexusElite

It's recommend when replacing knock sensors to replace the harness as well, my bet is the harness.

JazzyQuinn

That would probably explain why I see both codes, and sometimes only one or the other. I'll try replacing the harness and hopefully I wont need to buy new sensors again. Thanks for the insight I'll let you know how it goes.

JazzyQuinn

I have also had a couple mechanics tell me that it is likely a problem with the computer. Has anyone ever heard of anything like this?

Mythotical

Some other circuits have known issues but not the knock sensor circuit. Not all mechanics are good at diagnostic, too many of them are just certified parts changers. And that's coming from a mechanic!

JazzyQuinn

Good to know, makes me more comfortable about moving forward with the harness replacement. I'm still waiting for a quote from a local mechanic and Lexus Dealer for to see what they will charge for this fix.

Thanks for the help

LexusElite

Yeah I have a hard time believing the ecu is bad, replace knock sensor harness and see what happens. From what I remember the harness and sensors sit right on top of the block and after being hot baked for so long they get brittle and break, even though you can't see it, internally broken wires could be the cause.

JazzyQuinn

The local shop and Lexus dealer never called back about working on my car. As frustrating as that is, I cant be too upset because my car has mysteriously started running fine again. Its been about 5 days now with no problems and no check engine light. Ill post back here if the problem returns to keep you guys updated.

JazzyQuinn

So the problem has returned and it was riding so rough the other day that I had to pull over and erase the codes to get home smoothly. The next day I found a reputable shop that quoted me $385 in labor and $475 in parts, a total of $860 for the job. With the knock sensors being about $200 a piece I'm wondering if I should just replace the wire harness and save $400...

I'm caught in a catch 22. I'm almost sure that the wire harness is the problem since its odd I see both codes or one at a time. But I would hate to have to go in there twice if the problem isn't fixed I'm worried about the possibility of aftermarket knock sensors being the culprit but is there a way I can tell what kind of sensors are installed, and if they are the proper OEM sensors? Also could a bad wire harness affect and damage the sensors meaning I should replace them anyway?

JazzyQuinn

Decided to play it safe instead of rolling the dice and I replaced both sensors as well. Picking up the car from the mechanic today.

CoryMiller

I'm having the same issue though my codes are not intermittent. Replaced both sensors and the harness.

I hate my car.

JazzyQuinn

Hmm that's frustrating I've heard that its possible for the wire to become grounded which could maybe describe your problem. Also are you using aftermarket sensors or the Toyota OEM sensors?

I've been driving my car for couple days now and she is running good with no issues. I will post back if any problems return but hopefully my problem is solved.

yeskay

quinn:
where did you buy the oem knock sensors and harness. does replacing just the harness also cost that much labor. i was quoted a labor of 280. can you provide the part numbers

JazzyQuinn

My mechanic ordered the parts so I don't know the part numbers but heres a link for the wire harness. http://www.partsgeek.com/gbproducts/...rvwaAh4n8P8HAQ

For labor your basically just paying for them to remove the intake and get in your engine. So it should cost the same amount of labor whether you replace the sensors or harness or both. If you just replace the harness you may save some money since the sensors can cost up to $200 ea. But you risk having to pay labor costs again if the problem isn't solved.