GM OBD Readiness monitors - Damn you GM

Knuckle Dragger

Mayor of Simpleton
Staff member
Lifetime Gold Member
Nov 2, 2002
16,937
Waddell AZ
From what I understand, it can take months for EVAP to set. CA is being strangely merciful on that one... probably too many people complaining to refs
I've already paid my reg, just can't get my tags until this damed O2 Heater registers.

It is, we can't get it to set at all sometimes in the summer. Starting temp never goes low enough LOL.

Arizona let's you miss one, they don't stipulate. Cali isn't doing you any favors by restricting which one.
 

Knuckle Dragger

Mayor of Simpleton
Staff member
Lifetime Gold Member
Nov 2, 2002
16,937
Waddell AZ
An 02 Vette is just an old OBD2 system, just go for a long drive to get the long term fuel trims set and you should be fine. The 2 pre cat O2's should light off pretty fast me thinks, the post O2's just monitor oxygen output to see the efficiency of the cat converters.
That's basic operation but the readiness monitor is more complicated then that.
 

Twisted_Metal

Administrator
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Lifetime Gold Member
Feb 26, 2004
31,661
Bloomington, MN
An 02 Vette is just an old OBD2 system, just go for a long drive to get the long term fuel trims set and you should be fine. The 2 pre cat O2's should light off pretty fast me thinks, the post O2's just monitor oxygen output to see the efficiency of the cat converters.
That explanation makes it sound easier to remedy than moving to North Dakota. ;)
 

Phil G

Veteran Member
May 3, 2004
961
Tucker, GA, USA
Fighting the same thing on my 1999 Pontiac Grand Prix GTP! Kinda hard to put miles on when the local cops (revenue collectors) are going to spot that my tags on that car are a year out of date. Even though I have the documents from the smog test I can see one of them being a dick and writing me up just to make me waste my time going to court to have it thrown out!
 

tom3

Veteran Member
Aug 1, 1999
14,912
ohio
Seems like there would have to be a way to get that monitor on board. When the car was new it probably didn't have this problem for the new car owner to deal with. How did the factory get it working from day one?
 

Lowend

Administrator. .a car, a man, a maraca.
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Mar 25, 1999
16,850
San Jose, CA, USA
In Cali, you don't have to smog new cars for the first 4 years, so not an issue. More modern OBD systems aren't quite so difficult to deal with. My Subaru just needed to be driven normally for about 40 miles and everything would set. No rain dances or futzing with electrical load at idle.
To add to the irony, they don't even do a sniff test anymore at the regular smog station. They just use the on board sensors to confirm stuff is working.
 

Eddiesystematic

New Member
Oct 9, 2017
24
I've been trying to get a smog check on my 2002 Corvette for the last week. The weekend before the smog I (stupidly) disconnected the battery to replace a headlight motor forgetting that it would reset the ECM. Failed smog due to non readiness... my fault.

For the last 8 days I've been trying to get the god-dammed O2 heater to go ready. Done the drive cycle/warm up cycle (cold start, 2 min idle with AC/Defrost on - 55MPH drive for 3 min etc... )every day. Everything else is good. Even the EVAP which is supposed to be the tough one clicked over yesterday. No MIL's But HTR icon sits there flashing on my scanner.


I'm just venting - I'm sure like many others I'll drive the car for a few more days and for some mysterious reason the O2 heater will go ready for no apparent reason. Seems to be how it goes with Early 2000's GM's.

I guess I got spoiled by other cars where you just drove them for 50-ish miles and everything went ready with no drama.

<Sigh>
 

Eddiesystematic

New Member
Oct 9, 2017
24
I've been trying to get a smog check on my 2002 Corvette for the last week. The weekend before the smog I (stupidly) disconnected the battery to replace a headlight motor forgetting that it would reset the ECM. Failed smog due to non readiness... my fault.

For the last 8 days I've been trying to get the god-dammed O2 heater to go ready. Done the drive cycle/warm up cycle (cold start, 2 min idle with AC/Defrost on - 55MPH drive for 3 min etc... )every day. Everything else is good. Even the EVAP which is supposed to be the tough one clicked over yesterday. No MIL's But HTR icon sits there flashing on my scanner.


I'm just venting - I'm sure like many others I'll drive the car for a few more days and for some mysterious reason the O2 heater will go ready for no apparent reason. Seems to be how it goes with Early 2000's GM's.

I guess I got spoiled by other cars where you just drove them for 50-ish miles and everything went ready with no drama.

<Sigh>
You can pass the test with one monitor "not ready" in 2002 - 2 "not ready" up to MY 2000
I think the heater monitor runs after the car been sitting. I will look to see if i can find the enable criteria on my info system later on today.
 

Knuckle Dragger

Mayor of Simpleton
Staff member
Lifetime Gold Member
Nov 2, 2002
16,937
Waddell AZ
In Cali, you don't have to smog new cars for the first 4 years, so not an issue. More modern OBD systems aren't quite so difficult to deal with. My Subaru just needed to be driven normally for about 40 miles and everything would set. No rain dances or futzing with electrical load at idle.
To add to the irony, they don't even do a sniff test anymore at the regular smog station. They just use the on board sensors to confirm stuff is working.

How is that "ironic"?
 




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