I have a 2008 F350 6.4L, auto, with dpf delete and edge cts/race tuner.

I got stuck in traffic friday idling for almost 1hr and the check engine light came on and the pedal went dead so I idled home. The tuner is displaying a
P0652 code. The truck has a dead pedal when you put it into gear. In park, the truck goes into high idle at 1500rpms and you can't rev it up, more dead pedal.

Had a similar problem 3 week ago, left the truck running for 20mins while I was in my shop, came out and same thing, truck on high idle and couldn't move it cause of a dead pedal. I thought it was a fuel thing so I changed both fuel filters and poured a can of seafoam into it. Cleared the check engine light and it fired up and the pedal was fine, I took it for 1hr bag drive and all has been fine until now.

Could I have a plugged up egr? Where do to start guys? Any suggestions or ideas. Help please.

 

P0652 X X X Sensor Reference
Voltage B Circuit Low
This error occurs when the sensor reference
voltage falls below a minimum threshold. Low: < 4.75V Wiring to sensors, PCM

That is the code...not EGR related. My guess is it is related to your pedal.

 

It may not be the pedal, VREF is the reference voltage for a number of sensors. If VREF is being dragged down it can be caused by a failing sensor, a short in a wiring harness, etc. Given that the symptoms have appeard during static conditions when underhood and under vehicle temps will be high, it may be thermal related.

P0652 - Sensor Reference Voltage B Circuit Low
Description: Indicates the reference voltage (VREF) circuit is less than VREF minimum.
Possible Causes: VREF circuit short to ground
Accelerator pedal position (APP) sensor (9F836)
Diesel particulate filter pressure sensor
Power take-off (PTO) system or auxiliary idle control

Diagnostic Aids: This DTC is set due to an under voltage condition on the VREF circuit.

There is a rather long diagnostic test tree that involves disconnecting the suspect sensors.

Note: For DTC P0652, the primary causes are concerns with the APP sensor, diesel particulate filter pressure sensor, PTO/auxiliary idle control or VREF circuits in the PCM B connector

 

Where is the diesel particulate filter pressure sensor? Is that the sensor installed back into the dpf delete pipe? Can a person bypass this sensor some how? The exhaust gets so hot under there while idling its retarded, wouldn't suprize me if some sensor is melted or fried up!

 

 

thanks for the image of the sensor.

I tried to start the truck again this morning and high idle still remains and still has a dead pedal. I turned the ignition ahead and read the codes again. Its now reading P0500 which means something with the VSS (vehicle speed sensor).

Any body know where the VSS is mounted?

So anyways, I go under the truck and play with the wiring for the dpf sensor after finding out which sensor it is (thanks to the above photo), I start the truck 5 minutes later and no more dead pedal. WTF? could the wiring have gotten wet or something?

I took the truck for a 10minute bag drive and no more codes.

I'm baffled? Anyone?

 

Sounds like the wiring is suspect. I would look for a exposed wiring somewhere. That is what the orginal code was trying to indicate.

 

When I changed out my cat I noticed that the wire on the DPF sensor fit very loosely. Might want to check that yours is tight

 

I concur, particularly a wire / harness that is coming in contact with something hot like an exhaust component and started melting through the insulation.

 

Truck is still running fine, no more codes or dead pedal. so far anyways...

 

The problem is back again. dead pedal, truck idles up to 1500rpm's and stays there when started. Programmer is giving me that same code and tells me i have a bad exhaust pressure sensor.

 

So heres the scoop, the truck runs fine then the check engine light comes on and limp mode happens which includes a 1500rpm idle with a dead gas pedal, then the truck runs fine for a week or so then dies again and back into limp mode. This has been the case on and off for 2 years and almost a daily occurance for almost 2 months.

Finally got a chance to do some tests..........With the truck running, the V-ref signal at the exhaust pressure sensor reads 5 volts, V-ref at the gas pedal is 5 volts. Probed the wires right at the ECM and the voltage is the same at 5volts.

I drive the truck around until the truck goes into limp mode, check engine light with a P0652 code. I check the voltage again and it is low and varying from 2.5v to 3v at both sensors, I unpluged both sensors just in case the sensors were dragging down the V-ref voltage and its still low. I checked right at the ECM and same low voltage.

I pulled my ECM computer out and had it sent off for testing and repair. I received a call today. I guess something was shorting out and needed replacing in my ECM. All fixed and being expressed back to me.

Woo hoo! hopefully this 2 year headache is over.

 

So they fixed something in my ecm and something else could not be repaired. Got my ECM back in the mail, free of charge and dead on arrival. What a nightmare! back to square one. Ford wants $1400 for a new one, can't track down a used one. **** does this suckballs.

 

Dam dude that sucks. Problems like that sure put a bad taste in a guys mouth for a Ford. Hope it works out.

 

Any updates???