type Gendy

I recently picked up a great 98 EX with 169k miles. I knew it needed axles and brakes, but to my dismay the check engine light came on the next day, after being assured there were no other issues with the car. I pulled the codes and discovered a P0420 which i knew was (catalyst system efficiency below threshold), and could be very tricky to diagnose as i experienced on another vehicle. The second code was a P1456, which i was unfamiliar with. After a quick search i see its EVAP Emission Control System Leak Detected ( fuel tank) pressure leak; and also reportedly very tricky to diagnose.

Anyway i reset the codes, and they were gone for a couple weeks, and then came back. I reset again, and they returned another 2 weeks later, and i quickly realized, they both appeared when my fuel gauge would be one "notch" below half a tank. I always put a full tank in and run it low, and repeat. This has happened 6 times so far...

While I can do the research on the two codes as they relate to accords, and possible causes, i was wondering if anybody sees any significance to the codes appearing at a certain point in my fuel level. Anybody experience this?? Any advice on the codes is welcome, but i just found it very intriguing how it related to the gas gauge!

tim73

The catalyst, many times means teh cat needs repalced. You can run a check on your downstream O2 sensor. The evap leak, these are tricky, many times, it is a cracked or broken rubber hose. Smoke test is normally the best way to find it, if you have access to one.

MAD_MIKE

Test your fuel pressure when the tank is full, and when the code comes back.

If there is a pressure issue, this would set off the 1456 code and can affect the running of the engine to cause it drop below catalyst threshold efficiency.