netnut

I have a 2000 RX300. The check engine light came on a month ago. I took it to the Toyota dealer for regular service and the light. The code he found was P0171 and said the A/F Ratio Sensor needed to be changed ($273 for sensor, $116 for labor). Expensive :-( he also said something about "if the manifold is also bad it will be more work". That was prior to fixing the sensor.

All was well until this morning, the check engine light came on again.
There are no other symptoms, the car runs fine.

Just one other data point: the wife gets the tank to be pretty low before she fills up again. But it has never gotten empty.

I am new to this, any advice appreciated. Also a pointer to a reader I could buy for this car and my GS300 2001 would also be appreciated. I am computer savvy, but not auto savvy.

Thanks!

Netnut
2000 RX 300
2001 GS 300

netnut

Toyota called and said this time it is the MAF sensor and they will give me a price on that. Based on what I read here, I asked him to clean it first. Now I'm not sure whether the AF needed to be replaced in the first place. may have just been a dirty MAF :-(

Netnut

Lexmex

I have had the condition of a low tank and the CEL comes on. Whether they are connected I do not know for sure. If it was, I think it is probably the muck at the not causing a good combustion, hence a lean condition for a second or to, triggering P0171.

P0171 is so common and probably the most common error on the RX. Could also be a gas cap, O2 sensor or MAF (dirty or failed). It could also just be that you car ran a little lean for a second other than possibly dirty fuel and now it is fine.

I used to just pull the negative batter cable or EFI fuse and see if it pops up again soon after as opposed to a week or a few days later.

I now have my code reader, an Actron, that goes for under $100 USD that I got through Autozone. Take a look online and see what deals they have on these. Mine just tells you the codes and you can reset the check engine light.

However, some of the other CL people can probably mention to you about computer based ones with more telemetry. Given what I do with my car, I should probably have one of these systems, too.

Your throttle body could also be dirty. I had a string of CEL lights...cleaned out throttle body...and nothing since.

netnut

Toyota called to say $180 for the MAF, "it cannot be cleaned". I asked for the old one back.
As a bone to throw, labor is free.

Netnut

Bobk528

Several weeks ago, the CEL lit up on my 2000 RX300 and when I took it to my mechanic, the diagnostic code read P0171. They ended up changing out a faulty air flow meter for a total repair bill of $250. I have over 62,000 miles and this is the first problem I encountered. I still wonder whether it is related to my putting in a K&N air filter one month prior. Overall, it has been running nicely but I'm not happy about 16 mpg in city driving.

Lexmex

Another thing I should bring up.

When I used to use K&N panel filters, before I sacked my airbox, I ran into the dirty MAF sensor for the first ime.

One of my Uncles has an older OBDII scanner than my other Uncle with a new Actron OBDII scanner. The older one read a whole string of O2 sensor codes, while the new one just read P0171.

Cleaned off the MAF...and nothing on either scanner.

I clean my MAF every weekend before I go to the track. Just a gentle rub with a tissue and it shows just a little dirt.

LC1338

I've heard that cleaning the MAF sensor may get rid of the P0171 code but it will eventually show up again after a few thousand miles. I suppose if you cleaned it and the code was gone for up to a couple of thousand miles or so, then you can conclude that the problem is the MAF sensor. At that point, I would go ahead and replace it with a new one and hopefully get another 60K+ miles out of it.

When cleaning the MAF sensor be sure that you use a solvent meant for cleaning electronic components, and leaves no residue (99.9% alcohol for example). I’ve found a Lexus dealer in Arizona that sells the MAF for around $120 plus shipping. Standard Lexus dealer price is around $180. Replacing the MAF sensor is pretty straight forward and should not take more than 5 minutes.

TunedRX300

Of course they don't want to clean it, 180 reasons to be exact
I would clean MAF and see it is dirty or a bad MAF.

Todd

K&N Filters have been reported on all kinds of message boards as being the cause of MAF sensor failures, and all with due cause. The oil from the filters, especially from ones that have been "over" oiled, cause contamination of the sensor. Think about it, it makes logical sense.

Secondly, with all due respect adding any type system to increase air flow into the compustion chamber without adding headers or a larger exhaust system to increase outflow is a waste of $. You might produce a slightly more aggressive sound but will not see any real gain in horsepower.

Lexmex

Secondly, with all due respect adding any type system to increase air flow into the compustion chamber without adding headers or a larger exhaust system to increase outflow is a waste of $. You might produce a slightly more aggressive sound but will not see any real gain in horsepower.[/QUOTE]

Todd,

This is so true. Down here I have people I meet put in a K&N or other type of special air induction expecting huge gains immediately...and they don't happen.

My gains only came after doing some major work on the exhaust system along with a slight redesign of my intake system. Even after my first work on my exhaust system, I still was not packing enough power so I went further on a second phase and now I am getting more juice.

I am working on the idea right now of a headers system for my RX though I like most things for the RX, they have to be custom-made.

koolaidman

hopefully its not over a year ago. if its less take it back to the dealer