I have searched and from what've I seen, cleaning the MAF seems to be the answer. I did this last night and the code is still on.

History:
99 3.4 auto 4runner. Sucked up a bunch of dust during a trip about a month ago. During the trip, CEL pops up. Checked the CEL and it was a PO420 and PO170 code. Crap, I hope it's not the cat so I'll buy a new A/F sensor, which I needed based on mileage anyway.

Check the CEL and now it's a PO171. Put on the new A/F sensor (plug for Evan at Northridge Toyota - best price for this anywhere) and clear the code. 20 miles down the road, CEL again. F@#$@#.

Check the CEL and it's still a PO171. Clean the MAF w/ electrical contact cleaner (thanks Bob the mod for the info) and clear the code. 30 miles later and the next morning, CEL again. I haven't had time to check the code but I'm pretty sure it's PO171.

Any thoughts? BTW, I have a K&N FIPK, which I've had for over a year w/ no issue. It was cleaned before the code and after checking it last night, the the filter and tube are clean. I'm at a loss for what else I can try.

Thanks for any help.

 

Edwin, did you already put in a new MAF?
If not that is probably your next step (when cleaning fails to clear the code and you already did your A/F sensor).

 

If I remember correctly, I was told a P0171 is a "bank one lean" code. If "bank one" means cylinder #1 (or plug #1) could there be a problem with the spark plug or wire?

FWIW- My P0171 was caused by a dirty MAF. Be sure you cleaned ALL parts. Both the little glob covered piece and the little resistor looking piece (sorry to be so technical. ).

 

Yup, sprayed the electrical contact cleaner all over the sucker (technical term). I changed the plugs about 10k miles ago w/ dealer plugs but the wires are from '98 according to the wires themselves. Could these old wires be the issue?

 

No, I didn't change the MAF, just cleaned it. Do these go bad?

I haven't read of anyone else changing the MAF except the ones that have upgraded to a Supra MAF. If this is a normal PM part, then I'll suck it up. Is this really my last course?

 

I have heard of the MAF going bad. I have the same code again after being off for 6-8 months. I think it is time to replace the MAF and O2 also.

 

Does it run rough or misfire at all? Ever?
I had the same code (along with others) when my wires were toast. Replaced the wires, and all was well. May or may not be related..

 

Yes, they can go "bad" per se (ie meaning out of spec, then ECU will throw a code). Cleaning works maybe 60-70% of the time.....in some cases they just flat out need to be replaced no matter how much you clean them. You have a later model (99-02) so they shouldn't be too much $$$ from Evan out by you.

I assumed that P0171 was the only code you have right now.......if you have others concurrently, that might indicate another condition as Gapguy mentioned was the case with his. If P0171 is your only code, I doubt the wires are to blame for the CEL.

 

Save yourself any more trouble and just change it. If you cleaned it and it went away for 30 miles well then you have found your answer. Just replace it. I tried to clean mine to clear that code and my CEL never went away. I replaced the MAF and it has been good 4k miles later.

 

Sweet. I just haven't seen others saying they replaced the MAF rather just clean it. Do you mind me asking what it costs?

 

No, it runs great and doesn't misfire. Are you saying that after you replaced the wires, the code went away along w/ the other codes after just doing the wires? I want to change these out anyway.

 

I am having the same issue with my truck, but the difference is i have a 96 4R SR5... Different MAF unit. For prices, (for mine atleast), the 96's only are $600 for the entire unit. I would guess for yours cause it is able to unscrew out, itll prolly be between $100-200. Lucky for everyone that owns 97+ year models.

Forgot to mention I have not corrected the code. Im a cheap ass and am looking for a used one instead of buying a brand new one at that price. But I am going to try one more thing before I get a new/used one. Im going to have the fuel system pressure cleaned. thats about $140. So I hope that works!

 

Edwin, you could also try a junkyard nearby and see if you can get a used one for cheap.

Here's the P/N of the sensor you need:
22204-07010 (price..... https://www.yotatech.com/forums/show...&postcount=329 )

 

Thanks for the part numbers Jaime. Even better, they're only a little more than $100.

 

Yes, as soon as I changed the plugs and wires, the codes stopped coming.

 

I don't remember how much it was...i do know it was over $100. The guy in the vendor advertising that does 25% off has them for $88 shipped i believe.

 

Thanks all. Another reason why

 

Here is a used MAF on eBay if you can't get a used one locally cheaper:
http://cgi.ebay.com/ebaymotors/4RUNN...spagenameZWDVW

 

I had to replace the MAF on my 2000 Tacoma after only 60K miles. Unfortunately this was after I had already replaced the 02 sensor which was probably working fine but was twice as expensive. My fault for not reading up on yotatech first

in any case, I haven't seen the CEL since.

 

Weird thing is the code turned off this morning. Anyone know if this means the CEL cleared itself and I have no more issues, or what?