'03 P5, '17 Miata, stock AF
- Dallas, TX
- 2003 Protege5
...and of course I had just filled up the tank. I had read fuel level needs to be "25%-75%," but since fuel level hadn't quite dropped to 75% when the CAT monitor did reset, I think your 85% figure is more accurate. For a moment, I thought my using 93 octane may be the problem (my JDM engine and MP3 ECU want premium gas).Don't forget your monitoring conditions.
Your fuel level needs to be between 35%-85% for the system to be monitored.
Side note: I've heard that some folks fill up with premium to pass their inspections and that that actually works for them. I've also read that using premium gas in a car that doesn't need it can cause unburnt fuel to exit your tailpipe, harming your results (and the environment). Texas inspections just rely on the ECU and don't do an actual sniffer test at the exhaust, so it actually didn't make a difference in my case.