Why won't my car emission monitors get ready?
Car emission monitors like EVAP and catalyst fail to set despite long drives, additives, and completed drive cycles. This prevents vehicles from passing state inspections, leaving drivers stuck trying expensive repairs or chasing stubborn underlying trouble codes.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Clearing codes and restarting the drive cycleDid this help you?
- 2Fixing pending codes before running the drive cycleDid this help you?
- 3Leveraging state allowances for one non-complete monitor where permittedDid this help you?
- 4Replacing the gas capDid this help you?
- 5Replacing the purge valveDid this help you?
- 6Checking return lines and lines from the tankDid this help you?
- 7Leaving the old purge valve back on after testing itDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I need help I have two codes on my 2009 Honda Pilot EX-L. P0497 & P145C I inspected the purge valve and it’s good the gas caps seems fine.”source ↗
“I did try to change out the purge valve just incase and when I went to pump gas (mind you I was low on gas) It kept clicking like if it was full I had to keep pumping after multiple clicks.”source ↗
“I need some advice I do small work on my car like change out spark plugs, coils and small part like this purge valve, O2 sensor and such so I’m familiar with the idea but I need advice how to clear the codes to pass emissions test (NYC).”source ↗
“I did order a new one waiting on it to come. My thing is what if that doesn’t fix it what else do I do?”source ↗
“Its sometimes on and sometimes off.”source ↗
“I have been. The work maybe a bit too much considering the cars value”source ↗
“I cannot get the evap/cat ready.”source ↗
“I have driven it 120 miles over the past few days, used cataclean, ran the ac, let it sit overnight and nothing seems to work.”source ↗
“I feel as if I am running out of options and may have to settle for a very expensive repair”source ↗
Where this came up
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