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!

 

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.

 

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.