AdamArnold

I know a lot, and thenj I don't know a lot. Are all four sensors on a 2001 ES300 the exact part?

I already changed the on on the fire wall, and getting ready to shotgun the rest.

Are they all the same exact part?

Thanks folks,

Adam

http://www.youtube.com/user/tx644

artbuc

No need to shotgun. Codes will tell you exactly which sensor needs attention. What codes are you getting?

Lexmex

Welcome to the Club.

That's right no need to shotgun, so the codes would be helpful.

For your 2001 ES300, the part numbers would be the following (they're different from the RX300 as there is a slight variation in the 1MZFE engines of both vehicles):

A/F Sensor (2 of them in engine compartment one in front of engine one in back): Denso 234-9021

O2 sensor (after main catalytic converter below vehicle): Denso 234-4137

Amazon is one of the best places on price to get them (it's where I got mine last time).

Forget the P0125 code, I don't think I've seen a 1MZFE engine on this forum (either in ES or RX) forums require changing this (engine coolant temperature sensor) out and that being the problem. It usually accompanies one of the A/F sensor codes. P0171 is another code you also can see pop up with the A/F sensor codes.

The only time I have seen a P0125 pop up without one of the A/F sensor codes was driving back in the Florida Keys shortly after I started up the vehicle and driving home. Happened to me at least twice (two separate trips). I had not changed the coolant out since I had gotten back from Mexico, wound up doing that and the P0125 went away. Also a P0125 by itself will have a bit of hesitation (back and forth for about 2 to 3 seconds) just before the CEL pops up.

Have you disconnected the battery and the codes still pop up after driving for a bit?

AdamArnold

I was getting the ole' P1155 code. I changed the one by the fire wall, so I will assume it's the one by the radiator.

Disconnected the battery and it stayed off for a minute after restarting the light were back on.. I have a decent code checker, so by unplugging each one and checking the codes, I found the bad sensor(with the firewall one). Hadn't got to doing it on this one yet, thought I'd pick your brains first.

It started to stall when I first start it up cold recently, hoping that might be part of the bad sensor.

88kmiles, great car, I'll drive it forever!

Thanks for the help!

Adam

hypervish

The stalling when cold has nothing to do with the sensor more than likely.

Clean the IACV and it should solve the problem. While your in there clean the throttle body.

AdamArnold

I guess I need a Chilton book on her.

Any web sites offer pics or diagrams regarding cleaning the throttle body and the IACV?

With sincerest thanks,

Adam Austin

LA4Mead

Adam:
The IACV (idle air control valve) likely is pretty easy to clean. This is from memory, so check it out first. On my '99 RX300 with a cable-actuated throttle it's right up on top, remove the black rubber double intake hose clamps (I don't know the technical terminology) at both ends and pull it out of the way. If you haven't done this before, the whole double butterfly intake is probably dirty, as well as the components downstream. I use a good EFI cleaner, like CRC brand (Autozone, Napa, or Carquest should have it). My engine won't easily run with the intake hoses removed, but I get a helper to turn the starter. I hold the spray in my right hand and the throttle (at the cable) with my left thumb. Be careful not to overspray other parts of the car or yourself, and that there's nothing in the way that might get sucked into the intake. I tell the assistant when to start the car, but I work the throttle with my left hand to keep it running (with the intake disconnected), it will stumble on it's own and stall. The IACV (in mine) is on the right at the bottom. It slides up and down. I spray into the butterfly area and clean out the EFI system first. I use a lot of spray (and increase the throttle) until all the black stuff stops coming out the exhaust. Then I clean the IACV, slide it up and down, with the spray and a rag (engine off, don't get the rag near the intake with the engine on). Mine hasn't had a problem with the IACV, but I hear it's a common issue.
I clean up and reconnect everything, and likely the Check Engine light will stay on until the codes are cleared with a scanner or by disconnecting the negative battery terminal for 5 or 10 minutes ( I use this opportunity to clean the battery cables, which clears the codes)..

Normally, the engine should start cold or warm, without touching the throttle. I'm told, if you have to use throttle to start the car, the IACV is usually the culprit. A friend's older Subaru had this problem, and I just guessed, it was the same issue.

Let us know if this helps.

I am no authority. If anyone else can correct me on any of this, then we'll all learn something. Anyone?

P.S. I've never found the Chilton or other 3rd party manuals to be of much help. Nothing replaces the factory manual. Good luck...

carguy07

I don't think I would immediately go after the IAC valve if you have other codes. When my A/F sensor went out and the car was in limp mode it could have easily stalled (probably flood).

artbuc

+1. They don't like it when they lose an A/F sensor.

AdamArnold

Thank you, your explanation, is what I DID exactly as you wrote it, I was alone so I had to improvise. The butterfly was clean brass when I got down to it. Put I have a nifty 12" extension hose for the CRC spray cap, so I opened the throttle, stuck that down her throat and doused her good on both intakes. put the BIG hoses back on temporarily, fired her up and revved her up good. I then repeated the process, and so far, no more stalling.

But, I found this on another Lexus site that gives a deeper cleaning of the IACV which I may try if she starts to stalling again(sounds like a day of fun):


Thanks to all for a great club with excellent support!

Adam

here is me doing what I rather be doing:
http://www.youtube.com/user/tx644

AdamArnold

This is a valid point as well. I know the front A/F sensor IS bad, and I imagine it can send bad mixture info to the computer as well. But a good throttle body cleaning never hurt anyone! LOL

Thanks again and wish me luck on the removal of that AF sensor by the radiator, (Hell, by the output valves is more like it (LMAO).

Adam

LA4Mead

Adam,

Changing the front sensor (behind the radiator) is a piece of cake. The rear one (towards the firewall) is a bit more complicated, but not bad, either.

I performed a good pre-emptive EFI cleaning including the IACV before I installed new A/F sensors, too. I couldn't see dousing new sensors with EFI cleaner and dirty soot. I think you're on th road to recovery.

Keep us informed as to your progress.

Lexmex

Adam,

Once you change that A/F sensor, make sure to disconnect and then reconnect your battery. Let the vehicle learn the new parameters. Drive it for about 15 minutes with no sudden takeoffs. Drive normally and get up above 55 mph at least once. That should help Miles Per Gallon. I generally like to do this when it is a bit cooler out such as at night, because when I do this on a hot day, it does not quite work out right with the MPG later on. These vehicles's computers adapt to your driving habits, and a lot has to do with the initial time after you've reset your system. I use to play with this scenario a lot to find the best method to do the 1/4 mile.

LA4Mead

Please correct me: I thought the engine management system is dynamically updating as you drive after learning to deviate from the default settings.
If I drive for MPG for 20 minutes, and then with more abrupt throttle changes and bury my foot in, doesn't it update from the initial settings to match the more recent driving pattern?
Then, go back to a light touch on the throttle for a while, doesn't it then modify performance to match?
How long do settings "stay"?

I noticed on long drives when my friend uses the cruise on the freeway over rolling steep hills in So Cal, there's a lot of shifting between 3rd & 4th. When I drive the same hills using cruise only as a "guide" and manually overriding the throttle, it stays in 4th almost all the time, and I hear a more deep induction tone which I attribute to the engine management system "knowing" to hold 4th longer.



Thanks!

hypervish

I think what Lexmex means is that it does the most learning the first time you drive it after resetting it. The rest of the time, the car is adjusting the shift point for your driving habits.

I know when I let my dad borrow my car, and he returns it the car is reluctant to downshift. Because, he get's up to speed with a light throttle. Whenever, It's only me who has driven the car, it'll downshift right away when i want it. I drive with a lead foot, and the RX knows it. hahaha