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Check Engine Light on, Acura computer doesn't pick up a code??

5 November 2014
Winnipeg, Manitoba, Canada in the spring, summer a
Hi guys I'm a new 2005 NSX owner and I had a check engine light on and took it in to an Acura dealer to fix the problem. The Dealer says the computer doesn't pick up a code. Has anyone experienced this before? Any ideas? Another maybe unrelated issue is the charging gauge on the dash is showing charging at 16. So a high charge? What could that be? Faulty alternator? Thanks Olie
Check engine light means there has to be a stored code! Go to any auto zone or advance auto and get them to read the code for free.

Or perhaps there's a ground error in the circuit that lights up the CEL...
I have never had a MIL warning on my NSX (knock on wood!) so I have not experienced your problem. That said, does the code reader not detect a code or is the code reader unable to read anything from the ECU (you don't need to have a MIL warning light on to be able to read data from the ECU)? If they can't read anything from the ECU, the code reader may not be communicating with the ECU which could be as simple as a faulty connection at the OBDII port or a broken wire between the port and the ECU. You need to determine whether there was a communication problem or whether the reader is communicating with the ECU; but, is just not detecting a code.

The MIL lamp gets a constant 12 v supply from the dash and is lit up by getting a ground connection from the ECU when an error code is generated. If the wire connecting the MIL lamp to the ECU is grounding out somewhere on the chassis, the MIL lamp will light up even though there is no code in the ECU. If the code reader can communicate with the ECU, then check for a bad connection between the MIL lamp and the ECU.

16 volts sounds like the voltage regulator is buggered and is applying full voltage to the alternator field winding. Around 16 volts is typical for the open circuit saturation voltage on automotive alternators. Confirm that the voltage is flakey (and that it is not the dash voltmeter that has gone south) by using a multimeter to measure the voltage to ground. The spot in the engine fuse box used for jump starting would be a good test point. If the system is actually running at 16 volts, you could try retrofitting a new regulator / brush set on your alternator. I have never had much luck with that. I suggest new alternator or rebuild if you have a good source.

Really low voltage can trigger the MIL light because it causes the ECU to interpret that the sensing devices are operating out of range. In such case you would have a code stored in the ECU. I have never heard of that problem being caused by high voltage in part because I would expect the internal voltage regulators in the ECU are capable of managing a 16 volt source voltage just fine. However, 16 volts will lead to rapid aging of your light bulbs and eventually destroy your battery, so get the problem fixed.
other than the electrical explanation above I don't know of any reason why the cel light would illuminate without a code being stored.............and so the story will go on since your car has a checkered past...let us know what occurs.
After the warning light lit and before you took the car to the dealer, did you disconnect the battery, remove the clock fuse, or otherwise experience a loss of power? Or, did you run the car quite a bit (I forget the number, but I think it's starting the car 25 or 50 times)? Any of those actions will clear out the codes.
Sounds odd - I would pick up a code reader so you can see yourself. I find the peace of mind of knowing what the code is as soon as one pops up to be well worth the piece of mind.

If you really want to nerd out with your car, you can pick up one of the readers that syncs with a mobile device via bluetooth and get a full readout of your car's functions on your phone/tablet