2002 Taco continually throws code p1135

Hi all, I have a 2002 Toyota Tacoma Base model 2.4l with an automatic trans,. a couple months ago my check engine light started illuminating. I pulled the codes and it threw a p1135 air fuel sensor bank 1 sensor 1 (upstream o2 sensor) heater control circuit malfunction. I finally got around to replacing the upstream o2 sensor today, it looked pretty bad it had quite a bit of white residue on it. After replacing it I connected my scanner to the diagnostic port and pulled up the code p1135 again and hit the erase button to delete the codes. Afterwards I went to go run a quick errand and before I backed out of the driveway the check engine light illuminated again! I've never seen an ecm reset that fast! I tried deleting it again with my scanner and started the engine again the check engine light illuminated throwing out p1135! I read on one forum that you have to disconnect the negative battery cable for 10-15 minutes to actually reset the ecm because the ecm on these Toyotas don't recognize a new part without doing it this way. Is that true? Please help!

 

yes, that should solve the issue if that part was the issue. 10 min should do it

 

Ok thanks!

 

keep in mind the engine will run very rough initially as it re-tunes itself. should be normal in 1-2 days of driving.

 

Ok will do! Thanks so much! I will update in a day or two to let everyone know what happens!

 

FYI
Error codes will reset themselves when correct fix is made.
Disconnecting battery starts engine ready checks.

 

Ok thanks! I do know the correct fix has to be made for it to stay off. Just a little surprised it set itself that fast!

 

I've never had to reset the ECU after doing a fix, the check engine light goes away on its own once the correct fix is made.

 

OP your problem is not fixed I venture you have a open circuit some place in the heater circuit . I hope I am wrong Good luck!!!

Might be a corroded connection or broken wires.

You did use a Denso Sensor?

When the repair is correct and I clear the code it will not come back .

Then depends just what one works on I remove the negative cable I have enough sparks in my life.

 

Yes Bivouac it's a Denso sensor. I'll take what you said under consideration. I've also thought about the possibility that I may not have plugged the sensor wire in good enough, so I'll check that out too.

 

Ok just disconnected the negative battery cable for about 15 minutes. Then I reconnected it and started the engine the light was off but after a minute or so of running the light illuminated again! So obviously something else is going on. I need to do some more checking.

 

Sorry !!

 

Check your power and grounds at the sensor connector. The heater circuit should be the white wire and the white w/ red tracer. White/Red being HOT. If your're getting 12V on the hot wire then try loading the circuit w/ a test light and see if it lights bright or dim. Just because you have 12V doesn't mean it can carry any significant amperage if the wire is corroded down to a few strands. If it's dim it's showing corrosion or some other resistance in the circuit.

The computer controls the ground side. I'm not too familiar with Toyota's setup but the circuit could be PWM in which case you would see voltage on the ground side because it's being switched by pulses creating a square wave to control amperage and alter the temperature of the AFR heater. It might be a little harder to diagnose the ground side if that's the case depending on your skill level.

If you have a test light a quick check for circuit integrity would be to wire the test light in line with the heater circuit. Put a t-pin or paper clip in the test light's alligator clip and stick it in one of heater circuit terminals in the connector and then stick the pointy end of your test light into the other then start the vehicle and everything should light. If not, you have wiring integrity issues or worse case a computer issue.

 

Also do a visual inspection of the wires wherever it's possible to see them. Follow them back as far as you can and look for any obvious corrosion, any areas where the wires may be contacting hot areas or subject to abrasion.

 

Plenty of good advice already posted.

This thread (hint, scroll to the last post: https://www.tacomaworld.com/threads/p0135-a-f-heater-fault-solved-on-2-4l-2003-5-spd.411801/) would suggest that you should follow the FSM trouble-shooting guide and pay close attention to grounds, particularly at the cyl head. Good luck.

 

These are tricky to trouble shoot as soon as the exhaust temperature is hot enough the heater circuit drops out.

All heater circuit does is heat the sensor to the exhaust temperature gets hot then it drops out.

 

Hi everyone! Sorry it's been so long since I've posted the last update! I just jacked up my truck and set it on jack stands again today and started checking! I decided to start with checking the connection where the o2 sensor plugs into the wiring harness because I thought I might not have plugged it in good enough, I pushed on the plug pretty hard and sure enough I heard an audible click! Long story short I had to reset the ecm again and started the engine and no more check engine light illumination! I just drove to town to What-A-Burger a little bit ago and kept the engine running the whole time I was in line at the drive-thru the check engine light never came on once not even on the way home or anything! So apparently the o2 sensor was bad after all! I'll just chalk it up to a lesson learned to always check all connections anytime I complete a repair! Thanks to everyone for all the help and advice! Thanks so much!

 

Thanks for following up. You’re certainly not the first person this has happened to, and you won’t be the last. It’s not everyday most of us are changing o2 sensors, so no one can fault you for not knowing what to check for.

 

I am glad it was a easy fix.

See how one little thing can cause issues.

 

Yeah I know! Tell me about it! So does anyone know approximately how long o2 sensors generally last? The one I replaced was the original sensor and it lasted 141,000 miles! So it lived a nice long life! Lol!