P0135 Help ASAP

**WS6ICK2K** · 04-08-2009, 10:32 AM

SES popped back on and now its throwing PO135. I scaned it and it reads 02 Heater Circuit Malfunction. (Bank 1 Sensor 1.) I have LTs with ORY and have just recently been mail order tuned by Frost.

Any help? I figured the tune would take care of it, but apparently not. The inspection has already ran out. So I need to get this fixed ASAP. Any suggestions?

**mark21742** · 04-08-2009, 08:42 PM

Originally Posted by WS6ICK2K

SES popped back on and now its throwing PO135. I scaned it and it reads 02 Heater Circuit Malfunction. (Bank 1 Sensor 1.) I have LTs with ORY and have just recently been mail order tuned by Frost.

Any help? I figured the tune would take care of it, but apparently not. The inspection has already ran out. So I need to get this fixed ASAP. Any suggestions?

the tune deletes the rear o2s (sensor 2, bank 1 and 2) your still running and need the front sensors. check your wires running to the front o2s, I've heard of lots of people getting the wires laying on the headers and burning through/ grounding to the headers. if the wiring looks good you might need to upgrade to the vette o2s..... one of these 2 things should fix your problem

**supercharged666** · 04-28-2009, 04:10 PM

Hey WS6ICK2K!!!! Did you ever find out what the problem was with your o2? I am having the exact same problem. I got LT and ORY and had the ECM tuned by FROST and it was running good for about 3 mounths and then I through that fault code P0135 for the front left o2 heater circult. I tried swapping 3 different o2's in there and it still keeps coming back. Just woundering what you did to fix your problem??

**mark21742** · 04-28-2009, 04:15 PM

Originally Posted by supercharged666

Hey WS6ICK2K!!!! Did you ever find out what the problem was with your o2? I am having the exact same problem. I got LT and ORY and had the ECM tuned by FROST and it was running good for about 3 mounths and then I through that fault code P0135 for the front left o2 heater circult. I tried swapping 3 different o2's in there and it still keeps coming back. Just woundering what you did to fix your problem??

check your wires running down to the sensor, sounds like you burnt/shorted a wire against the headers

**supercharged666** · 04-28-2009, 05:50 PM

OK, I'll check it as soon as I get a chance. It has to be the wires going from the o2 connector back to the ECM, since I already ruled out the wires going from the connector to the o2 by swapping it out before. Thanks for the help.

**mark21742** · 04-28-2009, 06:44 PM

goodluck man, I hate tracing wires

**supercharged666** · 05-07-2009, 12:49 PM

Ok so I visual inspected the harness going to the front left 02 sensor and there are no signs of any burns. I am also getting another fault code to go with the one I already have. The new fault code is p0351 Ignition Coil A. Primary/Secondary Circult Malfunction? Car still runs fine. I noticed that both the front left 02 and the front left coil both have a pink wire going to them. Does anyone know what this wire is, 5v, power???? If I possible got a bad wire maybe this could be giving me the 2 codes that i'm getting. Does anyone have a wiring diagram of the engine compartment?

**WS6ICK2K** · 05-08-2009, 07:50 PM

Originally Posted by supercharged666

Hey WS6ICK2K!!!! Did you ever find out what the problem was with your o2? I am having the exact same problem. I got LT and ORY and had the ECM tuned by FROST and it was running good for about 3 mounths and then I through that fault code P0135 for the front left o2 heater circult. I tried swapping 3 different o2's in there and it still keeps coming back. Just woundering what you did to fix your problem??

Sorry man I havent had time to get on here in a while. I fixed the problem and passed my OBII test with no problem. I decided to go ahead and upgrade the front 02s to Boshe 13111's a bit pricey but def worth it. After installing them the code hasnt popped back up in months.

The 13111s have a stronger heater and very long leads so that you don't need extensions to reach those long tubes. Frost recommended them to me, and after doing a little research, its what most people go with.

One of the down sides to Long tube headers is that the 02 sensors tend to not last as long.

Alot of times when you upgrade to ceramic coated longtubes. The headers themselves have small particles of the coating or flakes in them, which tends to cause a malfunction in the 02 sensors.

**supercharged666** · 05-08-2009, 10:35 PM

Yea I'm gunna keep the 13111's in mind but for some reason I think my problem is more then a bad 02 sensor. Like I said before I had swapped them from side to side and it had no affect. The code still came up on the left front. I think I might have a bad wire going to the connector, just having a hard time finding a good wiring diagram that shows all the wires. I know that the pink wire on the 02 is for the heater circult and I know there is a connection of other pink wire that all mate up and then go to the ecm. I just can't find a diagram that will show me it.

**WS6ICK2K** · 05-09-2009, 12:38 PM

Originally Posted by supercharged666

Yea I'm gunna keep the 13111's in mind but for some reason I think my problem is more then a bad 02 sensor. Like I said before I had swapped them from side to side and it had no affect. The code still came up on the left front. I think I might have a bad wire going to the connector, just having a hard time finding a good wiring diagram that shows all the wires. I know that the pink wire on the 02 is for the heater circult and I know there is a connection of other pink wire that all mate up and then go to the ecm. I just can't find a diagram that will show me it.

oh ok I understand, mine was a simple fix. I am not to educated when it comes to tracing wires either. Goodluck

**mark21742** · 05-09-2009, 01:33 PM

Originally Posted by WS6ICK2K

oh ok I understand, mine was a simple fix. I am not to educated when it comes to tracing wires either. Goodluck

I hate tracing bad wires

**Cutlass** · 05-10-2009, 05:58 AM

Originally Posted by supercharged666

Ok so I visual inspected the harness going to the front left 02 sensor and there are no signs of any burns. I am also getting another fault code to go with the one I already have. The new fault code is p0351 Ignition Coil A. Primary/Secondary Circult Malfunction? Car still runs fine. I noticed that both the front left 02 and the front left coil both have a pink wire going to them. Does anyone know what this wire is, 5v, power???? If I possible got a bad wire maybe this could be giving me the 2 codes that i'm getting. Does anyone have a wiring diagram of the engine compartment?

P0351 has to do with the control wire (purple) for the Cylinder #1 coil. The problem will either be the purple wire, the coil, the PCM, or the connections in between.
P0135 has to do with the O2 sensor heating circuit which is the pink wire (12 volts positive), the Black ground wire, the heater inside the O2 sensor, or the connections in between. Test (with key on) for power(pink) and ground(black) at the sensor with a test light, if ok...replace the sensor.

**supercharged666** · 05-12-2009, 01:30 PM

Ok so, I checked out the wires for the 02 sensor today. I connector my DVOM to the pink wire going to the 02 and connected the other end to ground. Turned the key on and got 12.5v. So I know i got good power going to it. Did the same for the ground side of the heater circult. Conneted one side to the black wire and put the other side to B+ got 12.5v. So everything checks out and leads to a bad 02 sensor heater circult. But I am still stumped about it because I had already swapped it out with 2 other 02's. How is it possible that I have 3 bad 02 sensors??

**Wesman** · 05-12-2009, 03:21 PM

Originally Posted by supercharged666

Ok so, I checked out the wires for the 02 sensor today. I connector my DVOM to the pink wire going to the 02 and connected the other end to ground. Turned the key on and got 12.5v. So I know i got good power going to it. Did the same for the ground side of the heater circult. Conneted one side to the black wire and put the other side to B+ got 12.5v. So everything checks out and leads to a bad 02 sensor heater circult. But I am still stumped about it because I had already swapped it out with 2 other 02's. How is it possible that I have 3 bad 02 sensors??

How often are the O2's going bad?? Its a common problem with LT headers to go through O2 sensors. I run the Bosch 13111's, and I've gone through 2 sets within the past year.

The problem is they don't get hot enough being so far down in the exhaust, and they start switching slow which causes the computer to throw a code. I've had codes for both insufficient switching as well as circuit malfunction. The first set threw insufficient switching codes, the second set threw codes for circuit malfunction. Repalced them with a new set a couple months ago and they've been good so far, we'll see how long they last.

**Cutlass** · 05-12-2009, 04:28 PM

Originally Posted by supercharged666

Ok so, I checked out the wires for the 02 sensor today. I connector my DVOM to the pink wire going to the 02 and connected the other end to ground. Turned the key on and got 12.5v. So I know i got good power going to it. Did the same for the ground side of the heater circult. Conneted one side to the black wire and put the other side to B+ got 12.5v. So everything checks out and leads to a bad 02 sensor heater circult. But I am still stumped about it because I had already swapped it out with 2 other 02's. How is it possible that I have 3 bad 02 sensors??

DVOM is a good test but a better test is to load test the heater circuit with something that will draw some amps through the wires. You could have a positive or negative wire thats good enough to show up on a meter but once you put a load to it, it doesn't work.
A test light works good for that (But not an LED test light). You can even make a test light with an old head bulb or a turn signal bulb. Those work even better since they draw more amps.

**supercharged666** · 05-20-2009, 02:14 PM

Ok so, I replaced the left front 02 with a new one. Code is gone and hasn't come back yet. Although I am still getting a sporadic code for ignition coil A. Which I am guessing is the #1 coil (front Left) Not really sure how to go about tracing down the problem since it only happeneds about once every 1000 miles? I went ahead and swapped the #1 and #2 coils to see if it picks it up on number 2 instead of 1 then I would know that it is a coil problem. Also the coils I do have are the RED MSD one's. Anyone ever have problems with them???

**Frost** · 05-20-2009, 08:36 PM

I have seen quite a few MSD coils fail.

To add insult to injury (they are $$$), they make less spark energy than the ultra cheap truck coils. I have routinely made over 800hp through stock coils though, so I'm not sure that they need a lot of help.

**NaviDyn** · 06-03-2009, 10:32 PM

Originally Posted by Wesman

How often are the O2's going bad?? Its a common problem with LT headers to go through O2 sensors. I run the Bosch 13111's, and I've gone through 2 sets within the past year.

The problem is they don't get hot enough being so far down in the exhaust, and they start switching slow which causes the computer to throw a code. I've had codes for both insufficient switching as well as circuit malfunction. The first set threw insufficient switching codes, the second set threw codes for circuit malfunction. Repalced them with a new set a couple months ago and they've been good so far, we'll see how long they last.

Yep. If you haven't blown the fuse that powers the heater, and based on his test showing B+ and ground good, the PCM is seeing to slow of a response. So it thinks the heater isn't bringing it up to temp quick enough.

**0rion** · 06-04-2009, 06:11 AM

heater codes are pretty common with headers. I had one that came and went for a while and I switched to 13111 sensors and haven't had one since.

**Wesman** · 06-04-2009, 04:38 PM

Originally Posted by NaviDyn

Yep. If you haven't blown the fuse that powers the heater, and based on his test showing B+ and ground good, the PCM is seeing to slow of a response. So it thinks the heater isn't bringing it up to temp quick enough.

Exactly. And the PCM has a very low tolerance for slow switching, any hint of a lazy O2 (or not hot enough O2 in our case) and it wants to revert to open loop and throw a code.