FJ Cruiser knock sensor question

[AttilaMonster]

A noob to the FJC forum but been around awhile in the FJ80 forum so flame away if you must.
Bought a used '07 FJ on May 22nd 2 days later check engine along with almost every warning light came on. So mad I didn't even waste time to pull codes just hauled it to dealer while still under 60 day warranty. Told me it was a catalytic converter so they replaced it on May 29th. June 24th decided to change plugs not knowing how long since last change. FSM calls for Denso K20HR-U11, what I pulled out were Denso platinum plugs PKH20TT. I cross referenced Denso website and decided to go with iridium. Denso recommended IKH20 so I put those in. I drove about 600 miles and all was good then July 4th started up the FJ and check engine light came on along with all the other warning lights. Hauled it back to dealer, service manager called and told me they needed more time with it but they think it is the knock sensor. They want to consult with someone before tearing apart the motor to replace it.
This is a long way of asking,......do any of you think it could be the iridium plugs? I mean if I need to go back to the platinum plug or what the FSM recommends then it'll save a lot of heart ache. What to y'all think?

 

[1911]

In my experience only, it is unlikely that spark plugs (even the wrong ones) would throw a code and trip the check engine light - but there is no way of knowing from here without having the trouble code(s) spat out by the scanner.

Having said that, personally I'm not a fan of expensive meteorite metal spark plugs. Plain-old ordinary Denso plugs work just as well for a fraction of the cost.

 

[AttilaMonster]

Thanks for the reply. Just in case anyone else has this problem I'll post updates. I'll speak to the tech tomorrow and see where I'm at. I thought I'd read somewhere that someone with a 4Runner swapped plugs and pulled knock sensor code then switched back to old plugs and didn't have the problem again. I guess I'm just grasping for anything at this time.

 

[Mtbcoach]

I agree with Lee in that it takes a degradation of the fuel to get the knock sensor to go off, unless the plugs gapped seriously wrong, it would surpise me that just a plug could throw a code. Yet, wierder things have happened...

 

[AttilaMonster]

Hmm, I'm running premium but come to think I usually run Chevron or Shell; however, the last tank was premium from Murphy's USA which I think is a Walmart brand. Can't recall how much of the tank I went thru before dash lite up like a Christmas tree. Something else to discuss with Toyota tech this morning.

 

[Diskord]

There really is no reason to run premium fuel, plain ole 87 is sufficient, unless you have a supercharger or turbo or high compression engine. Unless by premium you meant not low budget.

 

[AttilaMonster]

As a follow up, spoke to a Toyota tech and he echoed many of the things on the forum. "No need to run the platinum or iridium plugs, benefit doesn't outweight the cost." He did say that his experience is when you hit 25 - 30 K on a set of Denso IKH20 plugs to change them. He wouldn't comment on the iridium expectancy. I've run irdium in my Tundra up to 80K mi, pulled them and still looked good. Replaced at 92K mi. His report was that 1 of the 2 knock sensors had a short in the harness. I have to tip my hat to the technician as he told me he went ahead and replaced both sensors because it is such a chore to get to the 1 that was bad and that he didn't want me to experience any problems in the future. Thanks for the replies and comment. As Mtbcoach said "weirder things have happened...." and the FJ cruiser is a new one for me, at least with my FZJ80 I know what to expect.........well mostly.

 

[Mtbcoach]

Glad you found a solution and the dealership/tech took care of you...