Benjam1n

Filled up from about a quarter tank at a noname small town gas station, regular octane. Drove great about 200 miles then the next day (yesterday) she gets the CEL and limp mode on my commute home. Code reader says P0325. Reset and it came back on today. Could this be bad gas or does sensor definitely need replacement?

Plan to fill it up tomorrow with top grade premium and dump an injector cleaner in for good measure.

stirfryboy

Plan on replacing it. Could be the wire harness, at least replace that while you are in there. If it was me, I would replace both knock sensors and the harness, it's quite a bit of work. I would also do the valve cover gaskets at the same time if not done recently.

nsghtbrwry

Great advice. These vehicles are known to have oversensitive knock sensors. Do NOT use aftermarket replacements: the Toyota/Denso ones are resonant at 7kHz, and aftermarket ones often are just microphones that will pick up everything, giving you false knock sensor codes and sending your car into limp mode again.

That being said, I've used eBay knockoff "Denso" sensors on two cars so far with no problems ($36/pair vs $170 ea for OEM). They are probably just resistors...reason I used them other than cost is that my 1MZ's are in tip-top shape and I don't expect them to knock (they all get 87 from Costco). Of course, I'll have to rely on my ears and feel if they do start knocking for some reason.

In addition to both knock sensors (you'll need a 27mm shallow socket, btw) and the harness, I'll add that you should do the water bypass hose because if it fails, you'll dump water into the Vee and overheat the engine.

These are what I used, but you should check the part numbers (they're for VVTi motors, aka '99-'01):

harness:
bypass hose:
knockoff sensors: http://www.ebay.com/itm/301835362641...%3AMEBIDX%3AIT

crwys

I agree with the above. I also bought denso knock sensors for cheap on eBay and they have been holding up. Also replace
knock sensor wiring harness
coolant bypass hose
gaskets

maybe even your rear coils, spark plugs, fuel injectors, since they will be exposed. Thats up to you though depending on how your car runs, age, etc

Benjam1n

Update:

Putting in 93 Octane did nothing. Light kept coming back on. This month my emissions test is due so I traded the old girl in for a 2008 LS. She will be missed but performed her service valiantly and was extremely reliable. Hope next owner treats her right.