couldn't start after stopping for half hour, engine analysis found nothing

[frankluo]

2003 V4 Camry LE, 85K miles.
It happened to me three times within two months. After driving for 20-50 minutes, stop for 15-30 minutes, then the car cannot be started. When I turned the key, the engine was making some noise, just would not start. But a jump-start always worked, and after being jump started, I cannot get the car to stall again. It all happened in a relatively cold weather in Texas, which is around 40-50 degrees, but not sure if it is just a coincidence.
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It sounds like a bad battery, but I had it checked twice and it appeared to be good. I even paid $80 to Firestone to have them run a engine analysis on it and still found nothing.

Check engine light wasn't on, but a fault code was reported: P2238. Firestone didn't want to fix it, but suggested me going back to dealer to fix.

So any idea?

[Agent556]

http://www.dtcsearch.com/P2238/

sounds like an issue with the O2 sensor

as for the battery, if it's good then it may just have a low charge. Don't think its the starter if you heard it trying to start and it starts fine on a jump start.