P0135 Trouble Code - 02 Heater Circuit
 

First off I have a 2004 Monte Carlo LS 3400 V6. I have not made any engine/exhaust mods is well over 2-3 yrs.

I currently have a P0135 Trouble Code - 02 Heater Circuit (Bank 1, Sensor 1)



The scan tool shows the code above and the following data. I don't know what it all means and if this is a snapshot at some point in time?

• MAF(lb/min) = 2.9
• Fuel Sys 1 = CL
• Fuel Sys 2 = n/a
• Calc Load (%) = 14.5
• ECT (degree F) = 203
• STFTB (%) = -7.0
• LTFTB (%) = -17.2
• MAP (in Hg) = 18.0
• Eng RPM = 1687
• Veh Spd = 45

I guess what I am asking is where do I start to trouble shoot this?

1. check fuses
2. check pigtail is plugged into front 02 sensor
3. test amps and voltage of 02 wire (what should it read for amps??... should read 12 volts???)
4. ???
5. ???

KC:

What it means is that the heater on the O2 sensor is burned out...
all you need to do is replace it.:thumbsup:

Its referring to the sensor "after" the converter.:) Its an easy fix...

You merely have to unplug it and use an O2 sensor socket to remove the old one and to replace it with the new one!:thumbsup:

David hit the nail on the head. If you don't have a broken line in a harness, then next step would be just replace the sensor. These sensors are only meant to last about 75,000-100,000 miles (then the may begin to get questionable). Stick with an AC Delco or Delphi if you can for best results.

Thank you STUMPI and Maniac. I was not sure what sensor it was as there are 3 of them correct? There is an O2 sensor in the front exhaust manifold, and looks like an O2 sensor in the rear exhaust manifold and then one after the CAT in the U-bend. I am going to check out Summit racing to see if they have AC Delco or Delphi and also finally order that Magnaflow bolt in piped CAT so I get rid of the U-bend.

Our cars only have two O2 sensors. One in the rear mani and one in the u-bend. The one in the rear mani can have impact on fuel economy, so if it's pretty old, you may want to change that as well.

If you get the Magnaflow cat, hit me up if you have issues with a P0420 code popping up (I offer a small PCM service to delete the code and a couple minor PCM changes if you desire). :)

Thanks!

Correct, I was thinking there was an O2 sensor in the front manifold. There is a sensor below the front manifold on the block near the oil filter. That is what I was thinking of.

oopsey...LOL




Glad to help Casey! any time... YW:thumbsup:

I believe that sensor is the knock sensor (does not look like the oil pressure switch to me).

Pcm
 

do u tune pcms

I offer limited PCM adjustments. Please check this for more details:
https://montecarloforum.com/forum/pr...-3100-a-42773/