I put the Jet stage 1 performance chip in a couple of days ago. Service Engine light came on after a short drive. Noticed a slight difference in shifting. My tranny is automatic. The DTCode is:

P0706 TRANSMISSION RANGE SENSOR RATIONALITY

Can anyone explain what's happening? Has anyone had this issue?

 

Confirmed. I too had a few Check Engine lights come on within the first few weeks. 1 time it had enabled the 'limp-home' mode for the engine.
After doing a complete shut-down, remove Jet chip, reconnect stock harness connector - it drove home fine.
Next day reinstalled Jet Chip, double-checked connectors were fully seated and locked in with tabs, no trouble since...
I suspect the Jet Chip wiggled its way loose enough to confuse the computer into a loose connector-Limp-Home mode.
Going on 9 months with no trouble since.

Just make sure you disconnect the battery at every Jet Chip connect & disconnect.

 

I've had mine for about 2 months now. No problems at all, shifting is much smoother. Like Joseph said, make sure to disconnect battery and check all connectors for snug fit. Good luck.

 

I installed a Jet Chip Stage 1, about 3 months ago, and have had no problems. I am now considering selling it and buying the Stage 2. Since the original Chip, I have added CAI and will be adding exhaust very soon.

 

I had one installed for about 7 months with no problems. I've been thinking about going to Stage 2 myself, let me know what you think after you get yours.

 

Double check and make sure none of the plug pins are bent. The chip is very hard to seat properly the first time so check that also. Mine has been installed for over a year and no issues, except for the broken locking clips.

 

I took the Jet Chip out a few days ago and the service engine light has not been back on. Put it back in tonight and drove around.....the light came back on. Same fault code. The only thing I didn't do according to the instructions was to remove the entire ECM. I called JetChip....they advised I did that, so I did. I left the neg cable off long enough to reset the ECM. After installing the JetChip again, I drove around some more and the light came back on. Same fault code and one additional one .....P0443 EVAP PURGE SOLENOID CIRCUIT.

I have installed the AEM CIA and Magnaflow exhaust. Should I get the Stage 2 because of those mods? Would that make any difference?