Strange OBD code behavior - various codes pop up at the same time

[sixfrost]

Hi all.

I am having a problem with my OBD codes and Check Engine Light. It's an odd combination of codes and they all come up at the same time. I was hoping that someone could help me identify what it all could mean.

First, here is the scenario:

2001 GT. Check engine light started to come on a few weeks ago. I suspected a faulty MIL elliminator(s). They've worked perfectly ever since i installed a Bassani X pipe 3 years ago. After looking at them, i saw that the driver side MILE was touching the pipe and has melted. I replaced it with a new one. Reset the codes... The Check engine light cames back on LITERALLY after the first time i start the engine []

So i check the codes. ALL of the following codes came up:

P0135 - 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
P0141 - 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
P0161 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
These are all of the 4 O2 censors?? Why heater?

P1000 - OBD-II Monitor Testing Incomplete - is this just a normal "test complete" code?

P0443 - Evaporative Emission Control System Purge Control Valve Circuit
P1409 - Electronic Vacuum Regulator Control circuit fault
P1451 - EVAP Control System Canister Vent Solenoid Circuit Malfunction
( i was told that these may be caused if you fuel the car while it's running, dont know if this is true)

Ok, so i reset the codes again... Drive about 100 yards, shut the engine off, restart... the MIL is on again! Damn! After reading the codes again turns out the the SAME EXACT codes are back.

So i am puzzled, what would cause this combination to pop up all at the same time? The MIL elliminators are in good order. I am not seeing any drivability problems. What else would i look at? Are these vital codes? What could be causing them?

Any ideas are greatly appreciated. Thank you!

 

[triggz]

Sounds like a relay on which all of those are connected to is dead, or a big clump of wires is toasted somewhere.. Use a test light and start probing. Look for melted/stripped wires.. and find out what relay the emissions get power from and test it.


Do you have headers? Maybe something is resting on them and melted..

What bout ECU modification? If you've done any wiring to the ECU, check and make sure nothing is wrong in there.

 

[blackfang]

Your o2 is actually a heated oxygen sensor

As for the evap code did you get gas recently and not tighten the fuel cap?

 

[sixfrost]

Thanks!

No no headers. No ECU mods either.

I'll definitely take a look around the wiring, thanks for the tip.

Edited to add: i looked around for melted wires... nothing visible. As i mentioned before - the drivers mil elim module DID melt, that's why i thought originally was the problem for the Check engine light. I'll need to inspect the wires closer, but why would only ONE right/rear sensor cause ALL the 4 02 codes?...

 

[sixfrost]

Your o2 is actually a heated oxygen sensor

As for the evap code did you get gas recently and not tighten the fuel cap?

I checked the gas cap - it's tight. Again, all these codes (along with the O2 codes) come on TOGETHER at the same time. Even right after the ECU reset...

 

[blackfang]

Could be the ecu.

 

[bdcardinal]

the gas couldve been loft loose in teh past and its a memory code. as for having ALL the O2 sensors go bad, i would definately look at the wiring, and maybe find a source that they all went through. something like a relay or fuse. you will have to find a wiring diagram adn trace back from the O2s.

 

[sixfrost]

the gas couldve been loft loose in teh past and its a memory code. as for having ALL the O2 sensors go bad, i would definately look at the wiring, and maybe find a source that they all went through. something like a relay or fuse. you will have to find a wiring diagram adn trace back from the O2s.

Thanks for your reply.

Ok, but shouldnt the gas code(s) go away after i reset them? They come back after several resets. Together with all the o2 codes.

I'll look into the wiring though - it is a possiblility... I am curious if the o2 and the fuel wiring go through same connections somehow - and that's why they appear together...

I am definitely NOT a wiring expert though...

 

[bdcardinal]

something i would do, if i had access to one is to try doing a smoke check on the evap system. basically you fill it with smoke and look for leaks. also another thing to check is the purge valve and the charcoal canister.

when you fill up with gas do you stop pumping when the pump clicks, or do you keep pumping. if you keep pumping that will make the charcoal canister fill with gas and go bad.

 

[sixfrost]

i am not sure if any of my local shops would be able to do that...

I am guilty of overfilling the tank a few times! And in NJ where i usually fill up, the pumps are all FULL-SERV, and who knows if they overfill it, they probably do.

Do you have any idea how much "abuse" the charcoal canister might take? how fast or slow would it go bad? Would be any warning signs or would it just fail instantly?

Thanks for those tips, i'll try to look into this as well

 

[blackfang]

The EEPROM in the ecu stores all of your codes that have been triggered.

 

[chimchim]

also another thing to check is the purge valve and the charcoal canister.

Where might these items be located and how can I check them? Thanks.

I used the SEARCH function again. I feel great!

 

[Mike97gt]

i am at work right now so I do not have the time to give you a in depth response but those are all circuit faults. You either have a bad PCM or a wirring issue.

those EVAP system codes are not related to filling with the car running or the cap being loose. that would be a p0442 gross evap leak code or another leak code. these codes are circuti faults, and with that many of them out you have either a melted harness or a bad PCM.

I would be SHOCKED to find all those evap parts and all 4 o2 sensors went bad at the same time, so we know the only "part" that can cause this is the pcm. dO NOT GO BUY A pcm YET. because a melted harness can do the same thing, so first check ALL the wirring from the engine back to the evap system then we will get into the pcm diag,

check back tonight I will post more info on this

 

[Mike97gt]

3:00 am so I don't feel like looking stuff up but I wanted to bump this..

BTW check fuses too the heater circuits are fused off hand I don't know what fuses to check but I will look into this tommorow at somepoint

 

[chimchim]

Mike, can you elaborate on the p0443, please? Thank You.

 

[chimchim]

Mike, can you elaborate on the p0443, please? Thank You.

 

[chimchim]

p0443 / CEL / MIL

OK, problem fixed so far. I replaced the canister evap valve. bdcardinal told me in another thread that most of the time, a p0443 means this valve is bad.

From the front of the car, it is in the far left passenger side of the engine compartment below where the fuel lines come into the engine bay. If you follow the rubber hose that comes from the BACK of the upper plenum, this valve is inline on that hose after the sensor and before the charcoal canister.

For future reference and happy SEARCH users, it is part number E6ZZ-9C915-A. I did not disconnect the battery or shut the light off via a scantool. I drove the car about 10 miles and I turned it off and back on 2 times. Light went off on it's own. Hopefully it stays off. Thanks for the helps. :SNSign: