RenMar

Hello everybody,

Okay, let me describe my basic situation.
I’m here in the US for 6 month for an internship and bought a used Lexus ES300 2001 with 215k miles of from craigslist for $1700 (I know there should be something wrong)

AND I LOVE THAT CAR.

But last week the CEL came on - 2 codes one of the knock sensors and the downstream O2. After deleting the codes they come back on immediately after I turn the car back on… At first I had issues with the fail safe mode (no overdrive, weird RPM), but now my car is driving great. The RPM, Transmission and everything works perfect – I can only feel slight vibrations when I drive around 65-70 mph. My gas mileage is still okay (23 city / 28 highway). I switch between premium gasoline (93) and regular (87) with additive.

I had to learn that the knock sensor is an expensive fix and the best price I got so far was $700 with used original parts. I am now hesitant to put any money in a car that I want to drive only 5 more month.

I found this fix

https://www.clublexus.com/forums/rx-...ck-repair.html

and am really considering it – I just have to find someone who does it for me since my technical capabilities are limited.

My question is now if it is safe to drive the car as it is right now? So I know that a broken sensor might lead to engine damage, but with a car in that age/miles that could happen due to various reasons. Right?My plan was to drive that car as it is and if I start having issues like some described here (overdrive, no power, bad gas mileage) find someone to do the 15 minute fix.
Or would y’all suggest doing the 15 min fix now – no matter what?
Another possibility would be to sell the car for cheap and start looking into used cars again.But I hate the idea of selling my first Lexus...

What would you guys do?

Thanks and Best regards
Rene

speedkar9

I've had a friend driving with a supposed bad knock sensor for almost 2 years now on his 99 ES300. I don't think it will damage the engine mechanically, it'll just consume more fuel. Too much raw fuel going into the catalytic converter isn't good though, so you should look into getting it fixed soon.

I think $700 is a bit outrageous. The air intake box, plenum and intake manifold have to be removed to access it. You should also change the wiring harness and coolant tube that runs across the engine while your in there.

There's a few videos to show what's involved:

tomf

I'd fix it. I used these directions http://www.findonefindall.com/toyota...ock_sensor.htm to change mine. (note the directions are for a Sienna but the engine is the same. You don't have to remove the wipers as detailed in the directions. ) That being said I think you'd be fine doing the modification as long as you understand the risk of engine damage.

mugencivic

I have a 99 (same engine as your 01) and have been driving it with bad knock sensors since the day I purchased it (1.5 yrs ago). I gets annoying when i do a lot of stop and go driving, that's when the O/D kicks off. If you're doing non stop trips (short or long) the O/D doesn't kick off. You won't mess up the car if you don't fix it for the remaining 5 months. If you're going to replace it, I would replace the sensor with a new Denso one. If you go the used route, the sensor may go out again or may not be a good sensor.

As for the link you posted, it's a temp fix that I would do if I'm keeping the car for a while. I don't like selling cars that have been hacked that may cause someone else a headache down the road for them.

Ricko

I replaced the sensors and harness on my '99 this past weekend - about 4 hours of work and $350 in parts and a couple of new tools - runs great now. Label the tubes and parts as you remove them and you should be fine. The tough parts are the ground wire on the rear, the nut holding the power steering tube and the bolt for the rear mount. I picked up all the parts on Amazon...

Our '99 was occasionally going into 'limp mode' where it would restrict acceleration, run really rich and hot. After the fix, it's a lot quicker

The harness has to be replaced as it's usually the part that is failing first - but after all the work to get to the sensors, you'll want to replace everything so you don't have to get back in there again any time soon.

Good luck!

ES300NZ

if it were me, I would fix the o2 sensor.

The knock's are not a 'critical' sensor, the ecu might or might not care if they are disconnected. i can't be sure. but it's only a plug you have to unhook, and if it doesn't improve things you can reconnect it.

The o2's a teir one sensor, critical. You need that working for the car to run right. You can disconnect it and have the ecu replace it's (wrong) values with default ones. Which is a perfectly acceptable temporary solution. (a week or two), but the gas will get to you after a while.

given your situation, I would unplug both, and see how it goes. We're talking months here, just don't be that guy who doesn't tell the next owner what you did.

FYI, it would cost less than $700 to buy the tool and parts (second hand), to fix it yourself, and it's very easy.