Bocatrip

I had a check engine light thread in 2013 which turned out to be Bank 2 Sensor 1 . I just noticed my check engine light on with the word check. Once again, car is running fine and trans shifts fine. Gas cap is on tight. Only symptom I could mention is that my car has been slightly pinging under hard acceleration for quite some time...even years. I use 93 octane Chevron most of the time. Yes, I need the code/codes but prefer to take to my Indy rather than Autozone. My 2001 LS430 has 132,000 miles. Any clues? No smells and my gas mileage with 99% city driving has always been crappy since the day I purchased the car 8 years ago. I'm hoping for another 02 sensor, but would cringe if it's a catalytic converter. The car runs perfectly with plenty of power and no noticeable smells or symptoms. Any clues? PS...If the light is off tomorrow morning, will it be stored so that it can be pulled up?

NL5

I would invest in an obd2 scanner. I bought an Autel AL319 off Amazon for about $30. Works great, and no guessing why the light tripped.

Gronemus

You can get the codes for free from Autozone but you're going to pay to have the Indy do it. Sure, he might roll it over into the cost of the repair but wouldn't you like to know ahead of time what the problem is about?

Without the codes, any information guess offered up by anybody here is just going to be useless blather...

My 2¢...

Bocatrip

My Indy came up withe 2 codes. P0171 and P0172. Bank one lean and Bank two lean. He suspects but can't be certain it might be the MAF sensor. He blew it out with compressed air and reset the CEL. He needed more time to diagnose thoroughly before suggesting I replace the MAF sensor. Anyone out there with any feedback or suggestions? My car is a 2001 with 133,000 miles. Many years ago I did replace Bank 2 Oxygen sensor 1. Car runs fine when the light was on. Hasn't come back on, but I only drove approximately 15 miles since resetting. Any feedback would be greatly appreciated. Thanks all.

Gronemus

Strange that it's both P0171 (Bank 1 too lean) and P0172(Bank 1 too rich). I'd check the Y-pipe for an exhaust leak and if that isn't it I'd probably just replace the O2 sensor...

Bocatrip

No. That wasn't it. Both Bank 1 and Bank 2 are too lean.

Jabberwock

I'd call around and find a parts store that allows reasonable returns on parts and go buy a new MAF and install it right there in the parking lot (takes 5 minutes if you take your time). Some stores including Lexus dealer usually will allow you to try it out on your car since the install has no effect on the new MAF and return if it same day if it does not solve the issue. It may cure the problem and if it does not cure the problem swap your old MAF back in and return the MAF.

Bocatrip

Thanks Jabberwock. I've never heard that one before, but it's good to know. I see such a vast disparity in pricing on line for the MAF. Most are Toyota/Denso parts with Toyota/Lexus part number 22204-22010 and Denso part number 1976030. Prices start at $15 (most likely aftermarket) and goes to the low $100 mark. Average is $30-$50. Most parts have both Toyota and Denso part number embossed on the MAF. Does the ECM have to be recalibrated after installing the new MAF? Pictures show Toyota packaging even though they have Denso and Toyota on the packaging... Which is the best fit? I want the OEM part period!

YODAONE

Purchase a can of CRC MAF spray cleaner.
Also; Replace all.O2 sensors

Bocatrip

Replaced one 02 sensor a few years ago which was an OEM part. My Indy cleaned the MAF with forced air today. He mentioned cleaning with a spray might harm the MAF and didn't go there. Replacing the other 3 with OEM can be a very expensive proposition instead of replacing the MAF. I'm also considering going to Lexus for the $99 diagnostic and see where it goes. With Lexus they back it up 100% in case a wrong diagnosis. I could also go elsewhere with the Lexus Diagnosis if cost is too high. In the mean time, the car is performing fine, light is still off. I have time to decide. Decisions decisons! lol

rkw77080

Gronemus was right... P0172 indicates that Bank 1 is too rich. Otherwise, you would get P0174 for Bank 2 is too lean. Attached are the steps to troubleshoot.

Bocatrip

Thanks. I'm just hoping that my Indy is interpreting things correctly.. If not.. I'm going in the wrong direction.

Bocatrip

P0171 and P0172 were supposed to be that Bank 1 and 2 were both too lean. Is this incorrect?

Gronemus

There's a couple of problems with this. First, at least around here, there are no retailers that will let you return sensors or other electrical items. Some might if the device was sealed and it was brought back unused, in the original packaging. Face it, would you want to be the next guy in line receiving a now used part for your car? I know I wouldn't.

Second, depending on how one drives, this problem might take several days to reappear after the OBD system has been reset. So you might think that you've fixed the problem only to have it show up later...

Gronemus

You don't know this. This is the type of problem that generally takes time to trigger the OBD system. It is also the type of problem that can/will damage your catalytic converter. Find out what kind of diagnostic equipment and capability your Indy has or take it to the dealer to get it repaired...