Error Code P0125

100 miles should be plenty long enough for the ECM to go through a couple of drive cycles. Good job on the repair, and have fun with your truck.

 

Thanks! I'll take care of 0171 first! Should I worry about the 0125 since it seems to be either Bank 1 Sensor 1 or is it ECT (coolant temp sensor)?

 

Take care of the P0171 and see if the light comes back on. The P0125 is the code for the AF sensor.

 

Help!!! So I installed a new MAF sensor yesterday... truck idled great but terrible other than that. So bad, the truck wouldn't rev past 3000 without bogging completely, a tap on accelerator would only make it 'hink-up'... could new sensor be faulty, is there something else I need to do after putting in the new one? I got no codes after either way since I had to disconnect my battery....

Would my O2 sensors need to be changed after the new MAF and then it would run correctly?

Has anyone ever experienced this?

 

If the MAF was indeed bad, the ECU was making corrections for the inaccurate load reading (incorrect air flow) and this also effects timing corrections. These figures are learned over time in "cells" for various driving conditions. Replacing the part will have returned readings to normal values but learned behavior has not yet caught up. You would normally (in a shop) reset these adaptive values after the repair was confirmed and the vehicle would relearn the adaptives from base values.

No way to be sure without some scan data, but I have seen this behavior from many vehicles.

HTH

 

Update: I returned the after-market MAF since after another try, truck did not run properly. Installed Toyota MAF, now works great and 0171 code has not returned... I do have 0125 though. Is this bank 1 sensor 1? In other words, o2 sensor pre-cat?

 

That code is SUPPOSED to be for ECT (engine coolant temp) not high enough for closed loop fuel control. In other vehicles, a stuck open thermostat will set this code. All PXXXX codes up to P0999 are supposed to be standardized and all the P1XXX codes are maker specific. That said, this is a long known issue that Toyota did not always adhere to this. It was apparently a translation issue somewhere in the past.

The right way to check is to look at Mode 6 data in generic and see which system failed the test and go from there. I have seen this code set by an open heater in the B1S1 sensor. You can also watch the response from the sensor under snap throttle conditions according to Toyota, because sometimes it is a range and performance issue with the sensor itself.

Pins one and two at the sensor are the heater. You can take a meter across the heater to check for continuity. If the heater is open, replace it. Be careful as to where you buy the sensor. Pay attention to application and wire length. Stay away from universal fit connectors.

 

Here's an update: I'M FRUSTRATED!!!

I changed my ECT sensor last night, CEL with code 171 came back 20 minutes later. Now from my research online, seems like it could be:

- dirty/clogged injector
- O2 sensor (bank 1)
- vacuum leak

Any other ideas or advice? Seems like P0125 hasn't returned though, just the P0171.

Thanks!

 

If the computer was concerned about the condition of the sensor, it could have not believed the data from it for additional diagnostics. This is known as "blocking criteria" in the computer. In other words, if I use a sensor to test another system, I will suspend those tests if the sensor has a problem. The reason is that the second set of test results may not be accurate.

In the case of the P0171 code. That code indicates that the fuel system is reporting lean and the computer has corrected above a threshold the indicates a problem. It uses the O2 sensor to do this. If the sensor was faulty, it could hide another issue until the sensor is replaced. Toyota even has a chart that tells you what codes will block or disable other tests on the vehicle. Unless you are capable of diagnosing the P0171 code accurately, you may find yourself in a "toss parts at it" mode. That may be more expensive than taking it to a qualified technician for evaluation. Many things can be the root of a P0171 code, those you listed and some others like a MAF issue. Does your scan tool report freeze frame data? Can you get fuel trim information at idle, part load and wide open acceleration? That data can help point the correct direction to test.

It is not as simple as some parts houses would like you to think. There is no such thing as a code to part replacement list. I know that may not be what you WANTED to hear, but I hope you understand the answer.

Additional Question: Are you running an oiled filter on this vehicle?

 

Thanks for that response!

I was running an oiled filter but once I first encountered this problem with this code (and I found out that oiled could affect the MAF), I changed it to a dry one as a first step. I then cleaned my MAF afterwards, then later replaced the MAF with a new one. Now I have a dry filter, a new MAF and new ECT sensor.

I have made an apointment at Toyota for tomorrow in an effort to diagnose. They won't charge the diagnostics fee since I am having the same problem as I did when I first went to them.

I'm thinking it's become an injector issue - likely dirty/clogged.

My scan tool is very basic, only displays CEL codes.

I'll fill you in on what the dealer tells me tomorrow.

Thanks!

 

I'm having similar problems with my 98 V6 auto 4wd Tacoma. P0125 code followed by a P0130 and a P0133 code. Reading y'alls discussion, it seems like I might need to replace my O2 sensors, but I replaced them maybe 6 months ago with brand new ones. Do I need to replace them again or is something else causing these codes?

I have a high flow Magnaflow cat convertor on the truck, and I've been told that it may throw a code every-so-often because it's not filtering as good as a stock cat.

Please, I need some help with this. My truck is having sporatic idle with it high one minute and stalling out the next. Thanks.

 

Thread revival,
So I use a K and N filter and I recently cleaned it and oiled an got po171 po125, so I cleaned the MAF an wiped the oil off the filter some an put it back in and got a CEL again with just the po125 code.

Any ideas to correct this problem?

 

Now p1135 too

 

I was getting a 1130 for the longest time, due to a bad bank 1 02 sensor 1. The sensor was making my truck hesitate and choke-out during acceleration; so, I unplugged both my 02 sensors and am running without them till my new sensor comes. Truck runs in open-loop eternally now; but, performs way better.
Anyhow: after unplugging the sensors, 0125 is the code my truck is throwing now. So, if you get this code you may have a dead 02 sensor
Here's a post I found on another site in regard to this code:

"Johnc280 said: 10-19-06 09:14 PM
All 3 of the codes indicate a malfunction in B1S1 air/fuel ratio sensor. (what used to be an O2 sensor). There are a few tests you can do to make sure, but I would feel comfortable recommending replacing that sensor and clearing the codes.

Hope this helps.

John


Read more: http://www.doityourself.com/forum/passenger-cars-suv-service-repairs-no-trucks/281803-p-codes-0125-1130-1135-toyota-tacoma.html#ixzz3IYcgODOK"

 

Hey guys, I replaced the front O2 sensor but I'm still getting p0125. Is it actually the coolant temp sensor then?

 

So when you go to get a new one do you as for air/flow sensor or is it just an o2 sesnor

 

I just checked mine, and I have codes P0420, P0125, and P1130. I ran my truck for about a month with the P0420 code until yesterday, that's when I noticed P0125 and P1130. I bought an O2 sensor (upstream bank 1, w/ California emission) which came out to around 83.00 dollars... any suggestions on what else I should look into after the O2 replacement?