Check Engine Light 98' Tacoma 4-cylinder

I took my truck to Auto Zone. They did an analysis and stated that it was possibly and an air/fuel mixture system lean bank 1 (cylinder number 1 denotes bank 1). Probable cause is low fuel pressure, faulty MAF/VAF sensor, cylinder misfire condition, faulty H02S/AF sensor, or a large vacuum leak.

My truck runs good and I don't want it to break down. Any suggestions on how to resolve this situation, or experiences with check engine light conditions?
If I unplug the battery, the light will go off for a period of time.

 

The light will not likely turn off if you unplug the battery. The fault is stored in memory. If the lean condition is remedied, the light may reset after certain conditions are met (e.g. turned off and on a certain number of times and driven a certain amount of miles).

This fault code could be a number of things. I had a similar code on a Nissan Xterra once and I simply did a tune up (since I planned on it anyway). This included new plugs, wires, distributor rotor cap, distributor cap, air filter, cleaned the MAF sensor, and new fuel filter. A professional fuel system cleaning may help too.

If you have the know-how to do these things, then it is a cheap way to possibly fix the problem, and it's good for the truck anyway. If you aren't under-the-hood savy, take it to a shop and let them figure out the root cause of the problem. What I'm trying to say is that the items I mentioned may fix it, but it could be something else all together, so it'd be a waste if you paid a shop to do a tune-up...let them find the real problem.

 

I had the same truck 98 4banger 2.7 5 speed ext cab 4x4. One if you haven't changed the plugs I would. Mine would come on once a month I'd unplug the battery for awhile it would go off for another month. I finally replaced what I think is call the Pcv. Little round plastic canaster no bigger round than a quarter. It does something with the vac system and gets clogged up. Once I replaced mine the light never came back on. I sold it with 174000 miles on it still miss it!!

 

The light would turn off for extended periods of time once I unplugged the battery. I cleaned the MAF, unplugged the battery and it is off for now. The code P0171.
I will have to look for the PCV. It is probably due for new spark plugs, wires, distributor cap. The truck has 90,000 miles with 65K from me.

 

I have an '01 2wd 2.4L 4 cyl and I'm having the same problem. Took it to the Toyota dealership and they told me it was lean 1 bank 1 AF sensor. I'm looking into replacing the sensor myself and saving a few $100 in labor costs. I've already replaced the spark plugs, and I'm wondering if this is a doable fix at home. Any thoughts or experiences?

 

Keep me up to date on how to replace that sensor. My check engine light was off for 1000 miles, but than came on the other day as I revved the high getting onto to the highway. I unplugged the battery and it is off again.

 

This code is set because of a lean condition. The best thing to do is to have a shop with a good scan tool to read the engine data so they can find out what is causing the lean condition or i have found that a dirty mass air flow sensor is the cause.You can get a can of mass air flow sensor cleaner for the auto parts and clean it yourself. It is mounted in the air intake tube close to the air cleaner and is mounted with two screws.Note let it air dry do not blow it with compressed air.

 

I'll post the fix pix up here when I inevitably fix it myself.

 

My MAF sensor has been cleaned about 4 times since I bought the truck, but I'll give that a shot again. Thanks!

 

If you have a shop that you use and trust then have them check the maf at idle and 2500 with no load before and after cleaning,it might need to be replaced. remember there are a few different thing that could cause this code that is why reading the engine data is important.

 

Replace the sensor last night. Quick and easy. Got it for $169 w tax from the Toyota dealership. I didn't take any pics though, sorry. The sensor was located in front of the cat headed toward the engine side of the exhaust. All you do is take off the 2 bolts holding it in place and disconnect the plug side. Then reverse to install the new one. Very, very easy. I drove my truck up on some ramps and did it in the drive way. Just be careful not to torque the bolts, my Dad felt the need to man handle one of the nuts and it snapped the bolt in half. Now I'm riding like this.

Remeber to have some spare bolts & nuts!