I recently got a supercharger installed on my '03 Z06 and the gas mileage went straight to hell. So I had them redo the tune last week. While I haven't calculated the MPGs yet to see if that problem has been solved, I did get a surprise when I started it earlier today:

Reduced Engine Power;
Service Active Handling;
Service Traction Control; and
Serivice Engine Soon.

I turned the car off, removed the key and the when I restarted it, the codes were gone.

I hit 44K miles today and I've had virtually no problems before (the traction control module did go out once and was replaced under warranty). Is it possible that the re-adjusted tune could have something to do with this or is it just a bad coincidence?? Has anyone heard of this?

 

With that varied array of codes it sounds more like a grounding problem than anything else. But to answer your question - certainly a modified tune can create issues that can lead to SES light and other unexpected things. You would really have to connect a scanner to know what the computer is doing though.

 

You did not disclose if your codes were current or history, and what the exact codes were....please post them.

 

The things that you stated as CODES are just DIC Messages;

Reduced Engine Power;
Service Active Handling;
Service Traction Control; and
Serivice Engine Soon.

Here is what you do to read the DTCs. If there are a TON of old DTCs clear them and see if any come back.

READING YOUR Engine Diagnostic Codes



The Diagnostic Display Mode is entered with the following procedure:

1) Turn on the ignition but don't start the engine. NOTE! You can read the DTCs with the engine running and or driving down the road but it can distract you. BE careful! Some DTCs clear themselves when you turn the ignition OFF!

2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.


Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.




Here is very good site that explains the DTCs:


http://www.corvette-web-central.com/C5DTCcode.html


http://www.obd-codes.com/trouble_cod...d-ii-codes.php



Make sure to include the H or C suffix!!

 

THANK YOU!! I'm going to do what you said tonight. I just hope there's some glitch with the tune and not something more serious (or worse, something serious caused by the supercharger/tune). I have the extended warranty and if need be, I'll take it in and have the dealer fix it. The only concern I have is with the intermittent codes; if they can't replicate the problem, they just hand the car back. The stability control system is critical and can cause serious problems if it goes bad and "senses" a skid that isn't happening. I suspect that the system's earlier malfunction - back in 2006 - caused me to spin out on the freeway. It was later replaced under warranty.