I got a "P0135 O2 Sensor Heater Circuit Malfunction" Error. I started getting the probably 1-2 days after a Magna Flow CatBack installation. I have searched the forums and have seen a couple references in threads with other O2 sensor errors, but no one really addressed this directly. (here is my search https://www.evolutionm.net/forums/se...archid=2559824)

Is this a dead sensor (shorted). I do have a CEL eliminator on my 2nd O2, and chance the temp difference being registered because of the back O2 resistor is now causing this because of the new CatBack??? Or should I just junk it and buy a new sensor?

Honestly with it like this I am seeing NO issues AT ALL wit the car driving. Even seems to have a slightly better throttle response.

If any one has some advice I am all ears, Thanks in advance.

 

the heater circuit is just a circuit with the o2 sensor as a resistor. all it affects is the warm up time of the o2 sensor. nothing else, really. the only reason there's a light is for emission purposes.

what'd you have to splice for the o2 sim? 2 wires from the o2 sensor are for the sensor readings. the other 2 are for the heater circuit.

 

I had to splice the back O2 by the cat. I had put on a header and down pipe that caused the CEL/SES. I had a cuatom cat back prior, but it was straight through no silencer int eh middle or anything. Only until the MagnaFlow went on did the CEL/SES come back on. Should I try removing the resistor on the Cat's O2?

 

(OP: I hope you dont mind me jumping in on your post)

I too have just had encountered the "P0135 Error"
I brought it into the shop, he said it would cost $249.00 EACH o2 sensor (Part Only), and although 1 was faulty, he recommended replacing BOTH!!! =S

I've done a quick search online and have found sensor's ranging between $28-100.
Is the cheap $28 missing any parts?!? and why are there different wire counts??

prices are through this link:
http://www.autopartswarehouse.com/se...ck+Replacement

any help is greatly appreciated.

 

If you're gonna use any universal o2 sensor then stick to the 4 wire as it has the right amount of heater wires. I also would stick with either Denso (oem brand) or NTK. I used a universal denso #234-4209 on my car for a few months now without any problems.