Keith,
See below. This TSB mentions only the battery, but there is also an ECM update; I needed both. Honda did the 1st under warranty and did the 2d at 43000 miles (out of warranty) at no cost since dealer said it should have been done at the same time. I think I got a letter from Honda; if you didn't maybe your VIN is out of the range; still if you get check engine from WOT, I'd be asking about the software issue.
Lewis

>>
http://www.alldata.com/tsb/Honda/11...-038/index.html

Honda Service Bulletin 05-038

Applies to 2005 Accord Hybrid - From VIN JHMCN3...5C000001 thru 5C006600

November 24, 2004

Product Update: IMA Battery Software Update

Background

The current battery control software can lead to IMA battery damage when the HDS is used in the generic mode, or a generic scan tool is used to clear IMA diagnostic trouble shooting codes (DTCs).

The current engine control software will celar the stored learned valuse sofr the CKP (crankshaft position) sensor if an HDS in generic mode, or a generic scan tool is used to clear DTCs.

With the CKP values cleared, the PCM could misinterpret the CKP input at high rpm as ping paired misfire (P0301/P0305) and set these DTCs.

Corrective Action

Update the IMA battery control module and the PGM-FI sofware using the Honda Diagnostic System (HDS)

Software Information

HDS Software Version 1.018.016 or later

Be sure to use the latest software available (curently 2.002.006). If the correct version of the software is not used, the HDS may incorrectly indicate that the system does not need an update.

 

Thanks for the info. Yeah, I remember that one. My car is outside of that VIN range.

 

My check engine light came on about a week ago ('05 HAH), and I have not been driving at wide open throttle. It might be because after I had put gas in it, perhaps I didn't turn the gas cap enough for it to click (don't remember). After the CEL came on, I tightened the gas cap to several clicks, and then after a few more errands it turned itself off (specifically, it failed to stay lit upon starting the car again). So I figured it was the gas cap being not tightened all the way that caused the problem.

But then a few days later, without having bought any more gas or fiddling any with the gas cap, the CEL lit up again. And then a day or so after that, it went out again. And then came on again.

Tonight I bought gas (with CEL in the ON state), tightened the cap way down, and after a few more short trips, the light turned off. So what's up with this??

Does the car somehow calculate the expected pressure in the tank, and compare it to actual, and set the CEL if calculation doesn't match actual (which presumably would happen if the gas cap wasn't tight)? If this gets recalculated only so often, this could explain why the light didn't extinguish immediately after getting new gas. But it doesn't explain (to me, at least) why the light would go on/off/on/off all on the same tank of gas.

Any ideas?

 

Take it to the dealer and have them check to see if any codes are stored. Or, AutoZone does code reading for free. You'll probably have a shorter wait time at Autozone.