desert_chris

Hey Guys I am new here, just bought my first Silverado and need some help:

Recently purchased a 2001 Silverado in private sale. The previous owner had recently replaced fuel pump and had an exhaust leak fixed (included all maintenance records with sale). I went to get it tested at emissions (Arizona) but they would not test it as apparently the ECU was cleared and not all tests (O2 sensor heater) had rerun. I need to get emissions done ASAP (on a temp plate fo the moment).

What I have tried:

After researching online, I downloaded the Torque app for my driod and purchased a bluetooth adapter. I am showing all ready except "O2 Sensor Heater" (which is what the same as they told me at the emissions test). There are no codes and no CEL.

Driving: There has already been over 500 miles put on the truck since the exhaust work was done on it. I have put over 150 (freeway and city) since purchasing.

I read the GM drive cycle info:

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from what I can tell the test for O2 sensor heater is the Idle with A/C on part. I have perfomed this part multiple times, still says "incomplete"

Anyone else had issues with this? Could this be a blown fuse or faulty sensor or something? Is there a software I can use with my bluetooth adapter that will actually let me monitor drive cycle tests as they run?

I read somewhere that a "cold start" actually needs to be below a certain temperature outside to run these diagnostics. If this is the case then I am SOL as its almost July in Phoenix and 115 degrees outside.

I'm about ready to take it to the dealership but really dont have money to blow on it if its something simple.

Any help is greatly appreciated.

desert_chris

Anyone??

shamrock246

it should throw a code for O2 sensor heater circuit and the code will tell you what O2 is bad pre or post cat and on what bank, you might just want to get a code reader or autozone will scan it for free i have had heater circuits fail in the sensors before and it always been the sensor but check the fuses and wiring befere you buy a new sensor


Sean

97 4x4 burb

desert_chris

No codes at all - checked it with my tool, then had Autozone check it. Totally clean of codes. Just says Heater diagnostic is incomplete...

skeeter5

Hi Chris,

Did you ever get this problem taken care of, and what "fixed" it?

Would you let us know.

Thanks,

desert_chris

Nope. I gave in and replaced all 4 O2 sensors last weekend (which involved disconnecting the battery and starting back at 0). First 15 minutes highway drive all monitors except O2 heater sensor and Evap ran. After 3 more highway spins and attempting to follow GM drive cycle as best as possible, no change. What really sucks is I just found out that I can get tested here in Arizona with 1 monitor not ready so I could have gone with just the O2 sensor heater not set. I guess when they rejected me the first time I was where I am now with O2 heater and EVAP not ready.

So my hope now is to get the damn EVAP to set this weekend and get it tested. I am baffled by the Sensor Heater. I'm still not convinced that its not related to the hot temperatures here in AZ. I have been trying to do my drive cycles at the crack of dawn but its still 80 degrees out.

I'll keep you all posted. If anyone has any more advice now would be a great time as my temp plates are up on Monday!

Thanks.

shamrock246

thats some wierd sh**,i read that procedure i thought sounded like some done on a dyno theres not enouph open space around here to do that


Sean

97 4x4 burb

Night Train

I agree, that is some wierd stuff going on there. I've always (knock on wood) been able to get an error code.

Something else that caught me off guard when fixing my own O2 issues is that Autozone only shows my 97 5.7 liter truck having 2 sensors when in fact it has 4.

desert_chris

Well my drama is over quite by surprise. I gave in and took it to a shop that I trust to diagnose it. Mechanic told me that the EVAP test will not run in AZ in summer as it is just too hot. Air intake needs to be between like 45 and 75 degrees. He had no luck determining why O2 Heater test was not running. CPU tested ok. As a seperate issue, I had him remove an aftermarket natural gas system that the previous owner had installed (totally unrelated, I just did not want it). There was a second ECU that controlled the natural gas system, he removed this and rewired everything back to stock. When I got the truck back I plugged in my scanner for the hell of it and was surprised to see the O2 Sensor heater test had ran! I drove straight to emissions and passed with the EVAP still incomplete (AZ allows one test incomplete). I can only assume that my issue with the O2 Heater was related to hack wiring on the aftermarket natural gas system. The EVAP I am pretty convinced from what I have been told and researched is very sensitive to temperature/atmospheric pressure, Jupiter’s alignment with earth (j/k). But the fact is, if you are in Arizona in the summer or Alaska in the winter it probably is not going to run. I hope this helps others jumping through these emissions hoops. From my experience, all tests except EVAP should run with a typical 15 minute cruise on the highway. My advice to those driving to death trying to get these tests to run is there probably is an underlying issue going.

William Zecena

Look I had the same problem with my EVAP sensor and what I did was I drove my car on a freeway for 20 minutes morning time and then I left it in my garage for the day and night next day drove for 5 minutes and my EVAP sensor became ready try that and good luck