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What's the difference between c-codes and h-codes?
I pulled codes today and got 3. 2 had an h-prefix and 1 had a c-prefix. Is there a difference between the 2? I'm speculating that h codes are historic possibly?
Also what do this codes mean and how can I fix the issues at hand? Car is a 92 coupe with an at.
Dome light? Does this refer to the light on the rearview mirror? (I would call that a map light rather than a dome light personally).
I replaced my EGR valve recently. It went from a c code to an h code. I cleared the codes after that. I guess I should try the disconnect the battery trick to clear even the historic codes.
Now who at gm thought they should make a system were a minor electrical issue with an interior light makes a light on the dash that says "service engine soon" illuminate was a good idea?
C is current code - malfunction is present now
H is history code - sometime in the last 40 key cycles a malfunction occurred.
Modules will self clear codes if malfunction doesn't reoccur after so many key cycles.
Faults in the CCM announce their presence as a "SYS" message in the odometer every 15 seconds or so.
If you're going to use the onboard diagnostics, you better familiarize yourself with these systems or you're going to be replacing a lot of parts that don't need replacing, and misdiagnosing things.
I've never seen "SYS" flash in the odometer before. But I have had the service engine soon light illuminate before? But I don't have any engine codes?
What's the difference between c-codes and h-codes?
