2012 GM Volt SHVCS Error Solved by VXDIAG VCX NANO

A 2012 GM Volt just threw the ‘Service high voltage charging system’ error. Torque pro shows the follow codes P1E00 and P1FFF.

Gm Volt Shvs Error

It was charging quite happily via the Zappi yesterday, but threw the faults when it was powered on this morning. It’s been very dry and warm recently so I’m guessing it’s not the charge port. The 12v batt has been on a ctek charger for most of the lockdown A quick check of the coolant level and it’s well above the seam as it should be. This makes me think it’s the coolant sensor.

Just to let you all know how I got on with this issue for your future reference.

After much online research I ended up buying a vxdiag vcx nano gm dongle ($119) and used it to reprogramme the HPCM2 module just like the dealer would. This turned out to be remarkably easy. You can get a 2 hour subscription to the acdelco programming website for about $45. Plus I have now have the dongle for future use.


1. Fix the issue, be it sensor or wiring. A 24kohm resistor ($1 for ten on eBay) bypassing the dodgy sensor and wiring has sorted it for me.

2. Purchase a vcx nano (GM version) from vxdiagshop.com. fast delivery.

3. Plug vcx into OBD port on car and laptop USB port. Power up car in service mode (hold power button for 10 seconds)

4. Go to the AC Delco website ACDelco TDS

5. Purchase a 2 hour subscription (approx $45). Download and install the required reprogramming software that pops up.

6. Choose module reprogramming and select the HPCM2 module. Reprogramming takes about 10 mins.

7. Select yes to the request to clear the outstanding fault codes.


This is a quick guide to follow

Chevy Volt 2012 HPCM2 Reprogramming with VXDIAG & Techline Connect


A dealer would only be allowed to fix it using the official parts and methods, so if it is definitely the sensor or wiring they would need to order and replace those parts, then reflash the HPCM2 module.

My guess would be a couple of hundred quid.