Code p06a8
Sensor Reference
Voltage C circuit
Range/performance
Confirmed
Permanent

In english, what does this mean besides take it in to get checked out?

 

Check your batteries. I am thinking they may need replaced. Load test them independently and isolated from the truck.

 

What ever happened to low voltage?

 

That is a good possibility, Senix. Both times I got the code was during the first start in the morning when the glow plugs would have been on and the batteries the weakest.
Hunter40

 

Im having a similar issue, I have code P06A7 which is voltage B circuit. basically there is a short in the reference voltage sent to the sensors to use and send a signal back the ECU. when mine shorts the boost gauge pegs at 40 psi and the turbo veins stick in one position. im trying to find a good ECU pinout to start tracing wires, if you take it in they may not be able to do much. I have looked everywhere and found a few people with the same issue an no one has a solution...

 

Orangestanger-
You are right. When I took it in they were unable to do anything because it wasn't happening right then. They told me to bring it in while the message is still on the screen next time.
Hunter40

 

So I took the truck in and was told they could not do much for me unless it had just occurred or I figured out what was causing the wrench light to appear.

After a month of driving it and trying to see what triggered the wrench light I can finally trigger it at will. If I have my foot on the brake with transmission in D or R and simultaneously press in the parking brake the wrench will appear.

I hope I can now take it in and demonstrate the problem so they can fix it this time. However, I do find it a little ridiculous that the truck would trigger a wrench light and throw a code that is so vague the techs won't even mess with it until the consumer figures out what triggers it. What is the point of the wrench light and codes then?

I will repost with the results once I get it back in the shop.

Hunter40

 

P06A8 - Sensor Reference Voltage C Circuit Range/Performance. The code means that the VREF circuit is out of range. VREF means "reference voltage' - a 5 volt PCM modulated voltage that is supplied to many of the powertrain sensors. It could mean an open in the circuit, short to ground, short to battery voltage or a shorted sensor. The pinpoint test is rather lengthy. With the wrench light coming on intermittently and the apparent lack of any other codes that might point to a particular sensor this can take time to diagnose.

Here is a full list of the potential faults from the Workshop Manual:

<ul type="disc"><li>harness circuits: VREF and SIGRTN</li><li>air conditioning pressure (ACP) sensor</li><li>accelerator pedal position (APP) sensor</li><li>crankshaft position (CKP) sensor</li><li>camshaft position (CMP) sensor</li><li>diesel particulate filter pressure bank 1, sensor 1 (9G824)</li><li>diesel particulate filter pressure bank 1, sensor 2 (9G824)</li><li>exhaust gas recirculation (EGR) valve</li><li>exhaust pressure (EP) sensor</li><li>fuel rail pressure (FRP) sensor</li><li>intake throttle actuator</li><li>manifold absolute pressure (MAP) sensor</li><li>power take off (PTO) system or auxiliary idle control</li><li>reductant pressure sensor</li><li>powertrain control module (PCM) (12A650)</li></ul>

 

The technicians finally found a wire harness above the parking break pedal that was shorting out. It was replaced under warranty. I have had the truck for a week now without any further lights or codes.

Hunter40

 

Thanks for reporting back.

 

I'm having the same exact problem now and can't figure it out what did you find out

 

i have same thing also get 63.47volts pcm i get turbo over boost also fuel psi reading and egts reading all over place my scaner is saying genertor line 2 frequncy 16 hz and fualt high i disconected alt and turbo still same my brothers snap on scan had pin outs but i have f750 his scanner said f550 idk if same but not sure how you check them its wrapped up pretty tight and i tried to check with plug un hooked dont seem to work im leaning to think its pcm is the issue i have place that maybe able to fix it but will be a lil bit before i can send it to them still need it i just put new batteries in being 19 they seemed to be getting weak i get alot of random codes because this issue i did talk to dealer he said alternator but dont think so when i compltly unhooked alt the scanner was reading same i have pin outs refferance from my brothers snap on scanner i dont get any psi on boost hose when feel it at idle when it says its pegged for boost if you figure this out let me know