CEL Won't Go Away

I have the P0141 code meaning bad O2 Sensor Bank 1 Sensor 2 (the sensor behind the cat).

The first thing I did was replace the sensor and reset the computer, but that did not fix it so I sent back the new sensor and got another thinking it was a bad product. That didn't work either, so I checked all the wiring looking for a short and found nothing. Next, I ordered another engine control computer from a junkyard in case the computer wasn't functioning properly, and still nothing.

The cat was just replaced recently so I don't think that is the problem either. I am out of ideas and any help would be appreciated. Is there a special OBDII scanner that can plug into the computer and test the voltages of the O2 sensors so I can narrow it down?

 

I had the same problem after changing out mine; my father-in-law suggested spraying some carb cleaner in the air intake (just make sure it is safe for your MAF). did it with the motor running and next time i started it, my CEL was gone and hasn't been back.

 

Try cleaning your MAF sensor first, but be sure to use MAF cleaner, readily available at any reputable autoparts store. Whatever you do don't use a Q-Tip to clean the MAF sensor wires, if you break them, it'd be a very costly mistake because a new MAF sensor costs well over $200.

 

Ok, I'll give that a try. Is it normal for the MAF sensor to cause a bad O2 sensor reading?

 

Yes very. Make sure to clean it with sensor approved cleaner. You can get some from radio shack.

 

Will a product like this work, CRC Electronic Cleaner, or is there something special for the MAF?

 

Yes that will work. They sell that at walmart. Make sure its completely dry before you put it back in. Also might as well clean your air filter.

 

and a heads up, the metal plate on the top face of the maf (part you see when its bolted into the intake) comes off, so dont hold it by the top. I was holding it by the top spraying it down w/ the MAF sensor cleaner when it popped out of the plate and i had to do a juggling act to stop it from falling to the cement...

 

what brand of sensor did you buy? P0141 is bank 1 in a 3rz btw not 2

 

Sorry, I meant Bank 1 Sensor 2.

 

is it a bosch? cuz those can be a little screwy

 

I'm having the same problem with my newly replaced O2 sensor. I had already done the cleaning mentioned above prior to installing new sensor as well as checking wires.

 

Don't just clean the sensor...take a ohmmeter/multi meter and check the specs across the pins it states on the FSM. If they aren't within specs, cleaning it won't do much. You'll need a new sensor.

They do go bad, and they aren't cheap. There like $312 from the dealership..like $180-220 from other places.
Your better off taking a multimeter to a pick n pull and hoping there is one still there..and getting it.
Alot cheaper.

 

Only use OEM Denso 02 sensors. Go to denso's website and look up the oem fit part number, then buy it from Rockauto or ebay. That's what I did and bought my OEM sensor off ebay for $50. No more CEL.

 

Don't mean to thread jack... My CEL came on a few days ago (first time ever) but turned off a couple days later by itself. Should I still take it in and get it scanned? Or is everything fine now?

 

I'd scan it ^ the code(s) will still be stored in the ECU.

It could be helpful to check it now, fix something before another problem arises.

 

Cool, thanks. My buddy actually has a nice scanner so i'm gonna have him scan it.

 

Well I haven't had a chance to clean the MAF sensor yet, I couldn't get one of the bolts off. But I was looking at the O2 sensor again and noticed that it is a little different style than most others. The owner before me just had a new catalytic converter and exhaust pipe put on as well as a new O2 sensor before I bought the truck. The sensor that was installed is mounted by a nut welded to the exhaust pipe, there is no oval shaped gasket like on most sensors. Is this a problem, or if I order a new Denso sensor to replace it will it still mount correctly without that gasket?

 

so the o2 sensor has a bung that looks like this?: (just an example off google)



if so that is aftermarket. Our taco's o2 sensors bolt on using two studs/nuts.

 

Correct, I talked with the guy that did the work and he said he went that route because it was much cheaper than buying an exhaust pipe from Toyota with the bracket. He said he had tested the sensor he installed and it was sending the correct voltages to the computer, but for some reason still turns on the CEL. I think I'll just get a cheap scan tool and scan the computer for any other codes every now and then.