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Stock Boost Gage not working, P0108 code, truck runs fine

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6.4L Power Stroke Diesel Engine fitted to 2008 - 2010 F250, F350 and F450 pickup trucks and F350 + Cab Chassis

Stock Boost Gage not working, P0108 code, truck runs fine

  #1  
Old 01-01-2019, 05:15 PM
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Stock Boost Gage not working, P0108 code, truck runs fine

I need a little help figuring out what is going on here. My 2010 is throwing a P0108 code and the stock boost gage is not working, but the truck runs just fine and it's making normal boost according to the Edge Insight CTS monitor. The truck has full deletes (cat, DPF, EGR) and has a tow tune on it through an SCT. Mods are not recent. They were done 4 years ago.

I can't figure out why the stock boost gage isn't working but the CTS shows normal boost, and what's causing the P0108 code. MAP sensor was new earlier this year.

When I clear the codes while the truck is running, the stock boost gauge goes to max for 5-10 seconds, then goes to zero and the code returns.

Anyone have any ideas what's going on? I tried searching the forum but didn't come up with anything. Thanks in advance.
 
  #2  
Old 01-02-2019, 10:27 AM
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maybe this will help

AC8 DIAGNOSTIC TROUBLE CODE (DTC) 0108: BARO CIRCUIT HIGH INPUT
DTC 0108 indicates barometric pressure out of range high during KOEO Self Test or during continuous diagnostic monitoring. Possible causes:

Biased BARO sensor/PCM
BARO circuit shorted to VREF

Key on.
Attempt to induce opposite DTC.
Disconnect BARO sensor.
Check DTCs.
Does DTC 0107 appear?

Yes: REPLACE BARO sensor CLEAR DTCs and RETEST.
No: GO to «AC9».

AC9 CHECK FOR SIGNAL WIRE POWER SHORT
Key off.
Disconnect PCM. Inspect for damaged, loose, corroded or pushed out pins.
Connect breakout box. PCM disconnected.
Measure resistance from Pin 84 to Pins 55/71/90/97.
Is resistance greater than 10,000 ohms?

Yes: REPLACE PCM. CLEAR DTCs and RETEST.
No: REPAIR short to power in signal wire Circuit 356 (DB/LG). CLEAR DTCs and RETEST.

there is a Barometric Pressure sensor inside the cabthe part numbers are F8UZ12A644AA or Motocraft DY-846.

 
  #3  
Old 01-03-2019, 12:48 AM
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I thought the barometric pressure sensor was integral to the PCM and couldn’t be replaced or removed by itself.

I haven’t looked under the dash to verify that, to be fair.
 
  #4  
Old 01-03-2019, 08:04 AM
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My mistake

its replaceable in 99-2003 models

 


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