Greetings
Happy new year ~ I'm Yang. And straight to the topic: I self-serivced my 2012 Cruze 1LT, 1.4T AT for two consecutive days, and after the second day, I got the trouble code (P3100) which I can't find any description. So I thought some guru in here might have some idea about the problem. Here is what happened during the two-day self-service (
Please read the red words for time saving):
Day 1: Engine oil change, nothing strange.
Engine oil and oil filter changed, engine air flow filter changed. And after the change, the oil life counter on the car had been reset. Then, a BlueDrive OBD scanner was used to scan any trouble code on the car, and non was found.
Day 2: Fumbled with throttle body and belt and reset the ECU.
TB:
As I'm having poor MPG (20/25 city/highway), I though it might be a good idea to clean the throttle body first (as cleaning is cheap).
Thus, I disconnect the negative battery cable (for ECU reset) and tried to disassemble and clean the TB. However, there was soooo little room for TB intake hose to get loose, so I failed to remove TB intake hose (and TB itself) and only cleaned the sensor (I think it is a temperature sensor, Bosch 0 261 230 042), in the TB intake hose before the TB, with the CRC MAF sensor cleaner, as there were a thick film of oil (touches and smells like engine oil) in the TB intake hose and on the sensor itself.
ECU reset:
As I learned from the Internet that the car would learn the driving behavior of the driver and it is a good idea to reset ECU so the car can relearn the driving style of the new driver, I decide to reset the ECU by disconnecting the battery cable.
The negative battery cable stays disconnected for more than 2 hours (during which I fumbled with the TB), and the connectors on both the battery and the cable were warped with electric tap to prevent form unintended shorts, and the contacting surface on both connectors were slightly brushed with a small wire brush to ensure good connection.
But, upon reconnecting the negative battery cable, a spark appeared between the cable and the battery connector, and then the car alarm set off (horn kept sounding about once a second, and lights flashing accordingly). I did panicked a little, but still kept pressing the cable to the battery connector (to prevent further sparking or surge to the electrical system) and hand tight the screw so the connection is temporarily solid. Then I pressed the unlock button on the car remote, and the car alarm shut off. Then I tight up the screw with the tool and applied some di-electrical grease over the connectors. At this point, I just thought the alarm thing is just a safety mechanism on the car that when the battery is reconnected and the car is unlocked, the alarm would set off to warn the user. But the fact proved me wrong.....
Belt:
After fumbling with the TB and setting off the alarm by reconnecting the battery, I wanted to serve the belt, as I just brought the car as used and would like do some preventive maintenance to it. So I used CRC electrical cleaner spray to clean the belt when the car was running(I couldn't find any belt cleaning agent in the local auto store and I thought electrical cleaner is safe enough for the sensitive electrical parts so it would also be safe enough for the belt), and then sprayed some CRC belt reconditioner to the belt while the car was running.
Again nothing major was noticed.
Final scan:
After all the above drama, the car was rescanned with BlueDrive OBD scanner, and to my surprise, the P3100 trouble code associated with fuel system showed up (no other code was found and no warning light on the dash). And no definition could be found for the P3100 code both on the BlueDrive APP nor the Internet. And after two days of driving and 5 to 7 times of erasing the code with BlueDerive OBD scanner, the P3100 code keeps showing up. After erasing code, it doesn't show up if the car just sit there idling (maximum idling for 14 mins from my experience), but then, if the car was driven for few minutes or restarted 2 or 3 times, the code would appear.
And just this morning, I found the 'service stablitrak' message on the dash while erasing the code with OBD scanner (just as the erasing starts the message would show up, every time as the cleaning starts). There is no warning light on the dash yet, and no radio, power stirring or ABS issues yet.
So I'm just wondering if anyone knows about the P3100 (associated with fuel system) trouble code? And did I fired my ECU or something while reconnecting the battery cables? And would the 'service stablitrak' thing get worse if nothing is done about it?
The car has only power train warranty left and as a student, I don't have much money to spend on the dealer for some expensive fix........
Please help,
Best regards 
