So, back story. A friend has a '96. Cant remember if its a manual or auto. She doesn't drive it much, although I had mentioned to her on several occasions that she really needed to run it once in a while, or at the very least put a battery tender on it.
Need less to say, several months ago, the battery went dead. She had a local mechanic ( who i also use for routine maintenance on my various vehicles ) replaced the battery. Started and ran just fine.
Fast forward to this week. She took the car in for inspection, and it wouldn't pass the emissions test.
Apparently, 4 of the monitors won't reset. The mechanic tried to run it through several drive cycles to reset the monitors, but it didn't work. reset the DME. Didn't work, natch. Replaced the pre cat O2 sensor. Still nothing.
The monitors that won't reset are:
Pre and post cat O2 sensors
Evap monitor
Heater circut monitor
Cat monitor.
Anyone have any thoughts?
Thanks.
Air leak because the old rubber got cracked? Dead MAF? Just brainstorming here. And what is "heater circut monitor"? Never heard of that one on these cars...
I just had a similar situation, but I had a check engine light and P0171 and P0174 lean codes. I found a crack in the lower intake boot and replaced that. However, clearing out the codes did not clear out all the monitors and I needed to do an emissions test on the car. Some of the monitors are harder to reset than others. I needed to do all sorts of driving. Make sure you have no check engine coded. If you do, resolve that problem first. Then take it out on a highway at speed. Just do all sorts of driving the more varied speed the better. It can take a week or two to clear all the monitors. I had to put 60 miles on the car to get them reset.
Clearing the adaptations on ECU should work better than 60 miles trips
You probably need to do some highway driving. My experience is that it usually needs a variety of conditions (as mentioned) to complete the testing. Well, at least with Toyotas.
You don't know much about US OBD2 drive cycles and monitors, do you?
Clearing the adaptions, or even clearing the codes, will require driving the car until every test condition is met and checked. There is a specific drive cycle that is recommended to meet all conditions. IT IS CAR?MODEL DEPENDENT.
/.randy
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