I bought a high mileage (200K) 01 ES300 last week for a very good price. I drove it 50 miles back to my house with no issues whatsoever, and drove approximately another 50 miles over a few days and I got a check engine light with the P0330 code. I read numerous posts here at CL about this code on various models and I understand the knock sensors and/or wiring harness are prone to failure especially at higher mileages, however there are a few odd things I noticed while researching this.

Several people have stated that the code appeared for them when their fuel level hit 1/4 tank. This is precisely what happened to me. I had been driving it without issue, and then it came on almost exactly when the fuel level hit 1/4. This has me wondering if it's really a bad sensor or if there is some other underlying issue. I only ask because I read more than one post about people having this code thrown when their fuel level is low. Some have suggested running a fuel system cleaner/additive, however I haven't seen any confirmation that this really fixed the issue and stopped the code from coming back. I've never been convinced that any of these additives work, however I figured it's worth a try so I cleared the code, added 8 gallons of 91 octane fuel and added 8oz of Berryman B12 Chemtool cleaner per the directions. After a morning of driving the code eventually came back. What I noticed is that it only seems to come on after the engine is hot. I drove a few short trips this morning and the check engine light didn't come on for a while, but then eventually when the engine was nice and hot it came back.

I have the diagnostics procedures from the service manual for basic continuity tests and I'm going to try that, but I think I may end up trying the bypass hack as a test, feeding the Bank 1 knock sensor output to the Bank 1 and Bank 2 inputs to trick the ECU. However, I've even read mixed results with this trick. Some say it worked, others say after doing it it results in codes for both banks (P0325 and P0330), leading me to think there may be something else going on. Do the P0325 and P0330 codes really mean the sensors and harness are bad?

If I do end up taking the throttle body off to replace the sensors and harness, at least I'll get an opportunity to do some preventative maintenance such as the coolant bypass hose, rear bank valve cover gasket, and spark plugs, hopefully giving me another 100K miles out of the car.

 

Before you bought the car did you hook up your code reader to check for pending codes and/or the readiness monitor? Not to sound cynical but the PO may have cleared the code(s) right before your test drive. You are correct it maybe faulty wiring, inspect for damaged wire insulation or bad connector. Good Luck.

 

Yes I checked the codes before I bought it, nothing was stored and all readiness monitors were complete except the EVAP system which took a while but did complete on the drive home. Like I said I drove about 100 miles before the knock sensor code came on.

I just poked around the engine compartment and was surprised that all the corrugated loom covering every wire is extremely brittle, so I'm not surprised if it's the wiring harness for the knock sensors causing the issue. I also found the brake booster vacuum line was cracked where it connects to the intake, also extremely brittle. I cut at the split and had enough length to reattach it. Is it possible that a lean condition could cause actual knock and trigger the sensor (without triggering any other codes) with the sensor providing an out of range value to the ECU? Or do the P0325/P0330 codes just mean the sensor isn't providing any input to the ECU?

 

Quick update on my P0330 code: I did the ECU hack, splicing the good sensor to both inputs pins on the ECU and the code is gone. I know, it's a dirty band-aid solution that will only last as long as the good knock sensor, but it's fine for now.

I got a P0442 code shortly after fixing this issue, which turned out to be an improperly tightened gas cap.