my99trd4x4 needs new plugs and fuel filter,engine code says 171 lean? - Toyota Nation Forum : Toyota Car and Truck Forums

98wrangler · 01-14-2005, 03:55 PM

Ok i went to toyota and got the right plugs glad i did but have yet to do the job. Any suggestions on how to do this. Also i tried changing the fuel filter but the threads will not turn. Is it righty tighty lefty lucy? Got my PBR blaster sprayed the hand brake cable thread area lots of road salt aka rust. Found my hand brake light went out

chronoti · 01-15-2005, 07:46 AM

try and get some box end wrenches for the bolts for the filter, after changing the filter reset the ecu (pull the fuse) and then check to see if it trips the cel again.

98wrangler · 01-16-2005, 01:07 AM

yeah will do or just undo the battery cable before i start the work. Could just be the oxy fuel inthe area cause my new Corolla is doing the same thing

OEMonkey · 01-16-2005, 10:20 PM

Yes, replace the fuel filter(maintenance due). But I'd test the MAF sensor(if your engine has one) if your getting a 171. Most of the time that's the culprit.

raycwang · 01-17-2005, 04:39 PM

I have a 99 4runner 4x4 has the same P0171 code for more than a month, I change the fuel filter, cleaned the injector changed the forward O2 sensor, the code still come back, what finally did it is the cleaning of the MAF sensor, its located behind the air filter. The fuel filter is a regular right thread, you need too good box type renches, one to hold it one to turn it.

Smoke · 01-17-2005, 08:07 PM

Are you using the K&N air filter?

98wrangler · 01-19-2005, 02:54 PM

Could the oil be doing something?

98wrangler · 01-19-2005, 05:43 PM

I went and got a 14 wrench special one with the three sides to it. I get better bite down on the nut but still cant get it loose. Tried pb blaster, tap on it with a hammer and still no luck. I went ahead and left the original fuel filter on. Did clean the MAF sprayed the elect crc stuff in it maybe to much and put in. Should i take back out and let it dry. Still got a stumble at stop lights like its not getting fuel.

djczer · 03-08-2005, 07:28 PM

Hello, I have a '99 4Runner and the Diagnostics also says "P0171 System too Lean (Bank 1)". I will try to clean the MAF and replace the air filter and spark plugs and report back. I have already replaced the 02 sensors and no luck. Any suggestions would be apprecaited it. What does the MAF sensor look like?

fadetoblack72 · 03-09-2005, 04:52 AM

If I am not mistaken it is the sensor on top of the air filter bor. I think you have to take the cover off to clean it. Not sure how to clean it but I have been advised against harsh chemicals such as Brake Parts Cleaner.
Hope this helps,
Jason

mburdick · 03-10-2005, 09:55 PM

First of all, Toyota recently told me that they do not replace fuel filters as a regular maintenance on the Tacoma's (mine's a 2000). Second, to replace a fuel filter you need flare nut wrenches. They have a special taper to them, and without the proper wrenches, you are likely to never get the nuts tight enough on the new filter to not leak.

I also just had my truck in for a mechanical problem, and they looked into my check engine light. It turned out to be a dirty Mass Air Flow sensor (which got dirty because I didn't change my filter for 25k miles). The cleaned the sensor and cleared the code. My code was indicating lean.

I had also just replaced my air filter and plugs and thoroughly inspected my wires (looking for signs of firing problems). The truck runs 100% better.