IndyRX300

I know this has been asked a million times and multiply the answers x5.

Of course the issue I am having happened to me while I was driving it and not the wife.

Her daily commute to work is primarily highway driving with a lot of stop and go. She also refuses to use the cruise control when she is able. End result 19.1 mpg

Wife and kids flew out to California to meet with family for the week so I decided that I would park my car and drive hers.

My commute to work is a 52 mile round trip with very little stop and go and avg speed is 65-70 mph using cruise control.

Well wouldnt you know it. The mpgs dropped dramatically from the 19.1 to 15 mpg.... Tires are properly inflated. Not running the a/c or heat nor the heated seats.

We either run 93 shell or bp on every tank.

Check engine light is intermitent and code suggests to replace a/f meter. I am sure they are the originals and they are pushing 160k.

My experience with these sensors when failing usually comes with the following symptoms.

The obvious , lower mpgs. Dying at idle and hesitation. Is it possible for the sensor to be bad and only causing poor mpgs???

I know this is a long drawn out thread and I truely appriciate you reading this. However, the answers that I have browsed during my searches came up with way too many opinions on what to do.

Thanks again guys.

thomas1

You know the best thing would be to get a scanner that can read live time and see what the sensors are doing. Then there would be no debate.

IndyRX300

I would love to do that but we are on a very limited budget. Especially after the airfare for the fam to go to Cali.

I am up in the air on what to do. At $4.20 a gallon , it may be worth it to just replace both sensors. Because at the rate we are using fuel now, the sensors would pay for themselves. If in fact that is they are the culprits. Being broke sucks!!!!

Thank you for the suggestion. I do aprriciate that.

code58

IF you do end up deciding you are going to replace the sensor(s), get them on Amazon. They have been as low as less than $80. but I think are up closer to $100. ea. now. Don't even think about anything but Denso sensors. They will have the Denso part # on them but are the exact same sensor as Lexus will want $225.- $250. ea. for. I must ask why you use premium fuel? I know the manual gives you the option and I don't know what the fuel in In. is like but my DIL's "99 RX has over 165K mi. on now on absolutely nothing but 87 oct. (reg.) fuel. I am the mechanic for the car and can tell you it runs like a top on it. Her mother has an '07 Lexus RX and complains about the fact it's the 1st. car she's had that requires Premium fuel at 20 cents a gal. more. She has about 85-90 K mi. on it now so is thinking about trading.

IndyRX300

We have tried running 87 and 89 . The mileage at that time was noticably less compared to the 93.

I work at amazon so I will be able to get a small discount anyways on them. I found one of the sensors last night on amazon for $50 or so and it was oem. I check the reviews and it was the correct part..

I need to do something soon. I was driving this because the MAF on my car has crapped out on me. When it rains.......

carguy07

The sensor that you are looking at on Amazon is the O2 sensor that is after the cat, not the A/F sensor that you need.

If the CEL comes on and you go into limp mode, it will run like crap and get awful gas mileage.

What opinions are you conflicted about?

IndyRX300

I have read it could be the MAF , ICV which could trigger the light. If I recall correctly P0171 is for the MAF.

Thanks to hypers link today on the diagnosis videos , I did take notice about a possible issue on the ICV

When I start it up , it stays at 1500 rpm until I put it in gear, I am just in a panic right now.


73 miles driven and just barely above a half tank

carguy07

Is that the only code you are pulling?

IndyRX300

1135 is the only code I have and it will stay on for a week or two , then just go away for about the same duration.

GS4_Fiend

iTrader: (22)

P1135 - A/F ratio sensor bank 1. It's common on Toyo/Lexus that the heater circuit on these sensors go bad and the sensor won't work properly and triggers the code. Replace the sensor and you should be good.

code58

That should be easy to check. The 2 black wires are the heater wires and you should be able to do a simple continuity check or an Ohms check and determine if it is bad. it shouldn't make any difference whick way (direction) you check because it's just a simple heater. When one went bad on my DIL's RX after I replaced it I took a die grinder and narrow cut-off blade and cut it apart. It was easy to see the broken heating element. When the CEL is on, if it shows continuity or Ohms then the problem could be elsewhere.