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Discussion Starter · #1 ·
Hi everyone -

The check engine light came on on my truck yesterday. It's a '99 PreRunner with the TRD package. It's got just over 70k miles on it, and I just changed the oil and had the transmission flushed.

Any idea as to why the light would have come on? What does it usually mean? Could it be an O2 sensor?

Is there any way to reset the light without taking it in to a dealer and paying hundreds of dollars?

Thanks,

- Steve
 

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TexasA&M said:
Hi everyone -
Any idea as to why the light would have come on? What does it usually mean? Could it be an O2 sensor?

Is there any way to reset the light without taking it in to a dealer and paying hundreds of dollars?

Thanks,

- Steve
It could be any number of things-
Bring it to some place like autozone that checks codes for free.

I purchased an OBD II scanner that plugs into my laptop. It allows me to check codes as well as reset the CEL.
 

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Dear Aggie,

This has happend twice to my 99. The first thing that caused it was a gas cap that was not sealing properly. The other is was the Mass Flow Sensor that became dirty. If it is that, you can clean it and you do not need to buy a new one. You will need to use a non-oil contact cleaner. This fix is way too easy. I forget the code was but if you do seach on the old Forum, that code and fix is well documented. If for some reason you can't find it there, just Google that code, you will be amazed on the documentation of that code. Way too many fixed this themself...

ANy way you need to find out the code, like the gent said go to Auto ZOne and they will do it for free. If it is the mas air flow sensor it will give you a number and the disciption will tell you nothing about the MAS.

Now to reset the check light, first check your manual. I beleive it will reset after a number of times of turning the key off and on(this is how I fixed the first problem with the cap) ALSO there is a fuse in the bank that is located under the hood on the left side~~~bad on me I forgot which one, all you have to do is pull it and let set for a couple of second and it will be reset.

I'm sure others here on the forum know which one it is.

A 99 needs a new cap any way but I would take to AZ to find out what it is...
 

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Discussion Starter · #4 ·
Thanks for the tip... I'm going to try and take it by AutoZone in the next few days and get it checked out....
 

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Let me know, it would be interesting (at least to me) what you problem was.
 

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Discussion Starter · #6 ·
Ok, I got the codes read....

PO171
System Too Lean
(Bank 1)

Any ideas? Is this the MAS error that you were talking about?
 

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Yea, a bank too lean code is usually a MAS problem. Remove it, squirt it with some contact cleaner, let it dry, and try it again. OR it could be 02 sensors, but 90% of the time it is a MAS that is dirty. This has happened to me on everything from toyotas to fords....
 

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Discussion Starter · #8 ·
Ok... I've done plenty of work to other cars, but (thankfully) have yet to really get dirty under the hood of the truck... where exactly is the MAS? What kind of cleaner can be used?

Also, what does it mean by Bank 1?
 

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Check Engine Light

2000 Prerunner with V6 and 69k miles, check engine light came on and would reset for only a short time. Since my extended warranty is running out took it in to check a transmission noise :mad: and the light.

Dealer is replacing the catalytic converter. And the transmission is FUBAR.
Dealer just called and wants $220 to install the CAT because of the TRD headers, dontcha just love the little fellers???
 

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your best bet it to test the connectors with a volt meter and read the resistance reading and it will tell you if it is working properly

if you are looking at the MAF meter, left to right, measure resistance at terminals E3, second pin and THA, third pin, you will be trying to read OHMS on your DVM at certain operating temperatures:
mine was dead, I paid $115 for a new meter
I can give you the specs if you email or call me
bob 630-688-4939 cell
 
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