I am brand new to this forum and brand new to GM's (anyone wanna buy a Mustang?). Anyway I bought a 2001 C5 a couple weeks ago and it threw P0135, P0141, P0155, and P0161 codes. All of these codes are Heated Oxygen Sensor Heater Circuit codes for all 4 O2 sensors. Research on this forum lead me to check the O2 sensor fuse and it turned out to be blown. So I replaced the fuse and drove it for a few miles to find it blown again.

Now about the car: It has Melrose Longtubes, RT high flow cats, RT x-pipe, and B&B Bullets. I got under the car to find that all the O2 sensor wires appear to be in good order and none of them are touching the headers.

I also live in CA and need to get the car smogged ASAP so any help would be greatly appreciated.

BTW I have been surfing around this forum a lot and really appreciate all the quality information being posted here. Nothing pissed me off more than the Mustang forums where 16 year old dumb asses would post a bunch of pretending to be technicians. Thanks in advance.

 

Can you tell me where the 02 heater fuse is located.

 

Pull the fuse panel cover in the engine bay. The map will show you where it is. Labeled "Oxygen Sensors". Hope this helps. Anyone have a solution to my problem??

 

I thought california dosent allow longtubes???

 

People often do things that are "not allowed".


If fuses are blowing, I'd immediately inspect any and all sensor wiring that's in close proximity to the header tubes, especially if they were touching. Look closer, there has to be something burnt there.

 

Ok. I'll take a closer look. Anyone else have any other suggestions. As far as the longtubes, you are right that they are not legal in CA. However, most smog shops do not bother doing a detailed visual inspection. The car actually passed all emissions but failed because the CEL came on during the test.

 

That is 100 percent CORRECT ..... The OP has a bigger problem than just a wiring problem.

No maker of Long Tubes has bothered (as in they wouldn't pass anyway) to get them certified by the Calif. Air Resource Board (CARB) .... which means that when the smog tech does the visual inspection of the engine area ... and asks for the CARB EO number (also known as a "Carb sticker") for the exhaust modifications ..... you loose

What other mods have been done ???? ANYTHING that modifies the engine intake, the engine itself (cam), the engine management system, or the exhaust (all the way to past the cats) and does not have a "sticker" is illegal. You are subject to some nasty fines for this.

Hopefully you have a "friend" in the smog business .... otherwise the OP should do a little more research on what's on the car and what's legal.

You have wiring that has been overheated and the wires are shorting. Look VERY carefully for ANY signs of exposed metal wire .... you have a short someplace in the O2 sensor wiring.

The problem with doing things that are "not allowed" in California is that the penalties are getting Draconian. If you FAIL the visual inspection and also get hit as a GROSS POLLUTER .... see

http://159.145.15.175/ftp/pdfdocs/grossvir.cap.pdf

for an explanation from the CARB of a CA smog check .....

Failing a smog test is a pain, the gross polluter designation can result in fines of $500.00 in addition to the costs of getting the vehicle to pass the test, plus your registrration fees.

I'm constantly amazed at how many posts I see bt people who list a CA address and when they say they are going to install LT headers and "hi-flow" cats (also no CA legal) and when it is pointed out to them it is illegal, they brush it off as "no big deal" ....

They will find out it is a "big deal" at that next smog check.

 

And it is gonna keep coming on ... the CARB OBD2 test (notice they hooked their test computer to your car's OBD2 port under your dash???) is not just a sniff test, it uses the federal EPA mandated software IN YOUR CAR to fail you. You need to find out what has been modded on the car ....

Many stations will "ignore" visual items IF the car passes the other two (Functional and Emissions) ... but you cannot even count on that anymore ... stations are getting more cautious because the BAR can suspend a stations license (even revoke it if there are on-going violations) and is threatening a random inspection program using "rigged" vehicles.

 

Thankfully I live in a small redneck town and not San Francisco or something. Getting the car to pass visual is not a problem. The car has already passed the sniffer but I just need to get this code problem cleared so I pass the OBD2 test.

Any pointers for inspecting the wires? The O2 wires all appear to have a protective sleeve on them. Thanks for all the input. You guys rock

 

Here's what I'd do .....

1) Disconnect 3 of the 4 sensors, and put in a new fuse

2) Turn the ignition ON

3) Take the wire for the CONNECTED sensor and try moving it around. Maybe even spray it with some salt water (12 ounces of water with 1 tablespoon salt dissolved) as you are moving it around. Do this for several minutes.

4) Turn ignition OFF and check fuse ..... obviously if blown, you've found the culprit. Replace that O2 sensor.

5) If the fuse is still good - disconnect sensor just tested and connect an untested sensor

6) Repeat steps 2 through 5 for the remaining sensors.

Best of luck,

 

Awesome advice. Just curious, what does the salt water do?

 

The salt makes the water an even better "conductor" of electricity. Pure water (distilled) is actually a poor conductor of electricity. Water with contaminants such as minerals, like your drinking water, is a "good" conductor of electricity. and water with salt (often called an electrolyte) is an excellent conductor of electricity.

The salt water will hopefully form a "bridge" between two exposed wires, so that even if you don't actually get them to touch, the circuit will "complete" and blow the fuse.