I did a search, but didn't find what I was looking for. I have a 1999 RX300 that's getting at most 10mpg, rough idle, jerky shifting, and white exhaust smoke. I checked my codes and got these in this order P0171 (system too lean), P0125 (insufficient coolant temperature for closed loop fuel control), and P1155 (air/fuel sensor heater circuit).

I cleaned the MAF already and the problem is still there. I think I might need to replace the MAF, but what other sensor(s) do I need to replace?

Can anyone tell me the right sensor(s) to replace, where to buy them cheap, and a location of a FAQ/Guide to install?

Thank you.

 

Bank 2 sensor 1, it's right there on the front of your engine block when you open the hood, that's the P1155 code.

The P0125 and P0171 often come on in conjunction with an A/F sensor code.

An advanced OBD2 scanner that can show the readings on each bank would probably confirm the issue. I'd have to defer on the installation and where to buy cheap to others, because I've actually done neither yet with regard to my own RX, but I know some people will show up and add to this.

When you tried to clear the codes (like pulling the battery cable off for a bit), did the codes come back up immediately after or soon thereafter?

P.S. the welding was due to cracks I had there back in Mexico.

 

I cleared the codes, immediately after the engine started jerking, and check engine light came on. I recently replaced my cracked manifold.

edit: where would I find an advanced OBD2 scanner?

 

^^ A good reputable shop would have access for reading A/F sensor values. But you have to pay for diagnosis.
I you cj=hoose to buy one , it would be very expensive. More than what you would pay for the bad A/F sensor.

These A/F sensors are typical problems in our vehicles.
So just replace Bank 1 sensor 2. Radiator side A/F and you should be fine.
Go for an OEM factory replacement or Denso brand only.

 

Alright thanks. I'm going to Napa now to pick up a before catalytic converter O2 sensor and a new MAF. It looks like I just unplug the old ones and plug in the new ones.

The only sensor that looks difficult to replace is the after catalytic converter O2 sensor, I hope it's not a bad sensor...

 

^^ Don't say 02 sensor.

It's an A/F sensor as in Air Fuel ratio

I'd also put off buying a MAF sensor until you replaced the A/F.
You might not need it.

 

Checked this website, www.densoproducts.com , for the proper part number and then checked the price at www.amazon.com and found the lowest price of $123.07 with free shipping. They also list a sensor tool you may need.

Other people on the forum have had problems with sensors other than Denso and Lexus branded.

Installation information is on the forum.

Bearbrew

 

Never mind I am ordering just the sensor off amazon for now. Thanks for the help guys.

 

I've been ordering a good part of my automotive stuff from amazon as of late.

 

Yeah I never noticed the deals they have on auto parts.

 

I was searching for a Denso MAF like the original I have now, but it seems like they don't make one anymore? What is a good MAF that will work correctly if I needed to buy one?

 

They're still out there, part number 22204‑21010. Stick to the Denso here (I won't say that on every part though).

http://www.trademotion.com/partlocat...layCatalogid=0

Not too long ago we had someone from Jacksonville, Florida who needed a MAF, but can't remember where they got it from. I'll defer to others if they know some other places.

 

fyi, i just bought a 2001 rx300 115000 had cel and vsc lights on. found hose from air box off fixed. used obd2 scanner to clear, code came back. replace both af sensors and cleaned maf cleared codes, runs great no lights. sprayed liquid wrench on 1 hour before removal of af,s. hardest part was unplugging back sensor from connector. you will be glad you replaced the af sensors. gas mileage normal. im in michigan and its cold i let car warm for 2 min. then drive normal no shift problems. also amazon had best deal on denso 234 9009 get the oxy sensor wrench set for 20 bucks very useful. good luck

 

^^I just put one in my father-in-laws 2001 Sienna (160k) a couple months ago.
It was around $150 at a Toyota dealer.
Same Toyota part # as in our RX's. 22204-07010

He kept popping a P0101 code. Some kinda range performance problem.

I told him I could find a cheaper replacement, but he said for the price diff. he'd go with the factory part.

 

Alright, thanks. I think I'm going to order a MAF from trademotion.com if I need to. I might have to because I remember the P0171 code coming up by itself awhile ago.