LT1DRVR92

After an engine shutdown (and expensive tow home) I got codes 16 and 42 using diagnostic ground plugs. I replaced the Optispark with a Petris unit. Engine ran fine but I still got a code 16. After running to operating temperature 10 – 12 times and driving about 300 miles the engine stalled. I could restart but it would immediately quit and temp gage would drop rapidly. The service engine light did not come on. I disconnected and reinserted each connector in the ECM. The engine started and ran fine but I still got a code 16. At this point, I was beyond my ability and comfort zone so I took the car to an experienced Vette technician. He checked all connections, ran the engine for about 4 hours and did two 15 mile test drive over a 3 day period. After the last test drive he got a code 15 in addition to the 16. He replaced the coolant temperature sensor and connector and cleared the codes. Engine ran fine with no stalls or shutdowns or service engine light. Just to be sure, today I checked for a code and got 16 again! But the engine runs fine – SO FAR. The tech believes that the shutdowns were due to the temp sensor and doesn’t think I should have a shutdown problem. The ECM was rebuilt and new plugs and wires put in within the last 5,000 miles. I am afraid to drive it very far as long as the code 16 keeps showing. Any ideas, suggestions would be greatly appreciated.

antfarmer2

Code 16 has been there since the new opti? If so might have got a bad one.

charliet615

If there is a "H" in front of the 16 code, H16, that is a history code. It just shows that at one time there was a failure. I think you'll be ok to drive....

LT1DRVR92

It is H16 but shouldn't that disappear when I clear the codes? It keeps reappearing which I thought indicated a hard code.

reg_255

Hey LT1DRVER92,

I'm having the same problem, also replaced my Opti with a Petris.
The only difference is mine has not stalled.

See my thread.

https://www.corvetteforum.com/forums...clear-out.html

Regards,
Roy

antfarmer2

Maybe two another guy is on his third MSD.

LT1DRVR92

Saw your thread earlier. I've also replaced most of the same that you did. Will be interested if you find a fix. I'm not a techie geek but think this all might have something to do with 22 year old computer technology. Love my '92 but makes me think that all mechanical was better - air, fuel, spark = go!

LT1DRVR92

It's an H code in the CCM test module but verifies as current in the ECM module. Since the car runs fine and I don't get a service engine light I'm wondering if it is possible for a code to be just sitting in the computer so not indicating a real problem. I'm not a computer / techie guy but have had weird stuff like that happen on my pc's.

LT1DRVR92

I finally fixed mine. Found a thread on the forum - clearing h codes, 3/29/14. This is what I did:
• Clear CCM codes.

• Start car without depressing accelerator

• Let car idle 5 minutes

• Drive car and run through the gears several times

• Drive at a steady 55 mph for 5 minutes

This process lets the computer “re-learn” the mixture codes for proper performance and should be done whenever the CCM is reset. Also, here's a link that goes thru the proper way to clear codes - also some other good info on C-4's. http://tech.corvettcentral.com/2011...trouble-codes/

Good luck

reg_255

I did this procedure about 2 weeks ago.
Check and the H was gone.

The next day started the car/shut off.
Rechecked H16 was back.

Regards,
Roy