P2135 and “Limp Mode”

During my Cross Country Drive I was having a reoccurring P2135 Diagnostic Trouble Code (DTC) accompanied by the car going into “Limp Mode”. When I returned from my trip, I dropped the G8 off at Synergy Motorsports to get things looked at.

It was determined that the “drive by wire” system used on the throttle of the G8 is “very sensitive”. As I understand it… there are two sensors (A and B) that measure the voltage going from the peddle to the throttle body, and then back. If the voltages going to/from are not the same the car throws the P2135 (TPS/pedal position sensor/switch a/b voltage correlation). Basically, the car goes into “Limp Mode” so there isn’t a chance of a run-away throttle condition (eg. Toyota).

With the installation of the TVS1900 Magnacharger, there were a few modifications made to the wiring harness under the hood. Some of these changes are done with connectors… and the theory is that one of these connections might be loose, resulting in the DTC. To remove the chance of a loose connection, we removed the connectors and directly wired everything.

I’ve only driven the G8 a couple hundred miles since the re-wiring, but so I’ve not yet received a DTC. Time will tell if this is the fix, but I’m fairly confident we are on the right path.