1986 Honda CRX check engine light when driving downhill

I have a problem with the Check Engine light. I live 9 miles from Santa Cruz CA which is at sea level. My home in the mountains is at 1,600’.
So when ever I drive into town it is down hill all the way. About half way down the Check Engine light comes on and that is the only time it comes on… The car is a 5 speed and has 175,000 miles on it. The car runs great and always passes smog tests. I’ve taken it into a Honda Service Center and they can’t figure out what is wrong. If I turn the engine off and then on again the Check Engine light resets. Any ideas what it might be?

Read the code when it sets one and that should tell you what it is. The codes can be read without anything more than a paperclip across the diagnostic connector and a notepad to read the “flashes” from the check engine light.

The codes are listed here;


Next time it comes on, stop, read the codes and post them back here and we’ll try and help.

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