P0108: Manifold Absolute Pressure/BARO Sensor High Input - anyone know what this is?

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lsintoronto

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The engine light came on today so pulled the code when I got home, cleared the code, restarted it and went for a short drive but the engine light stayed off. The LS seems to be running fine otherwise.

I'll see what happens tomorrow.

Code was P0108: Manifold Absolute Pressure/BARO Sensor High Input

Anyone know what this means or possible causes?

The car is a 2004 LS V8 Sport with 84K miles (135K km).

Thanks!
 
AFAIK, the BAP sensor is part of the MAF sensor assembly. (The sensor on the air intake tube just after the air filter.) You might try disconnecting and reconnecting the connector before doing anything more serious. I think that the possibilities are: MAF sensor assembly, wiring, PCM.
 
I wasn't aware that the LS had a BAP/MAP at all?

If the MAF measures the volume/density of air coming into the engine - for the engine to make it's gross afr adjustments, and then uses the O2 sensor feedback to make the finer adjustment - what would a MAP be used for?

Normally MAP are used in cars without MAFs, and uses a intake manifold pressure reading combined with the intake air temperature reading to calculate the intake charge density. It's crude and that's why MAF are now popular.
 
Quik LS said:
I wasn't aware that the LS had a BAP/MAP at all?

If the MAF measures the volume/density of air coming into the engine - for the engine to make it's gross afr adjustments, and then uses the O2 sensor feedback to make the finer adjustment - what would a MAP be used for?

Normally MAP are used in cars without MAFs, and uses a intake manifold pressure reading combined with the intake air temperature reading to calculate the intake charge density. It's crude and that's why MAF are now popular.
Click to expand...

My understanding (I don't have the emissions manuals, so I am not 100% certain) is that the LS does not have a MAP, but it does have a BAP built into the MAF. AFAIK, MAF systems require a BAP to avoid knock at high altitudes.

For the curious...

MAP = Manifold Absolute Pressure sensor.
BAP = Barometric Absolute Pressure sensor.
MAF = Mass Air Flow sensor.
 
got it - makes sense then that the BAP is in the intake tube where as a MAP would be in the intake manifold (behind the trottle plate)
 
So per the code, the Manifold Absolute Pressure/BARO Sensor refers to either the MAP or BAP (depending on what the car has - ie. same code for both systems)?
 
lsintoronto said:
So per the code, the Manifold Absolute Pressure/BARO Sensor refers to either the MAP or BAP (depending on what the car has - ie. same code for both systems)?
Click to expand...

That's my understanding...
 
Thanks for the info guys - I'll use some electrical contact cleaner on the MAF and see if that helps. The top of the air filter box also has a crack in it that's been covered with duct tape for a while so I'll have to find a replacement for that as well. I don't think the code would be related to this though as it's been like that for a few months.
 
lsintoronto said:
The top of the air filter box also has a crack in it that's been covered with duct tape for a while so I'll have to find a replacement for that as well. I don't think the code would be related to this though as it's been like that for a few months.
Click to expand...
that shouldn't make a difference since the crack is before the MAF and any air leaking in would be metered correctly, however if any thing else came through the crack like water or dust and dirt, then it could cause a problem with the sensor.
 
So, cleaned the MAF sensor on Saturday and reconnected it and it went one day before the engine light came on again this morning (used it on Saturday and then again today). Also cleaned the throttle body opening while I was there.

Any suggestion on what I can look at next? Thanks!
 
lsintoronto said:
So, cleaned the MAF sensor on Saturday and reconnected it and it went one day before the engine light came on again this morning (used it on Saturday and then again today). Also cleaned the throttle body opening while I was there.

Any suggestion on what I can look at next? Thanks!
Click to expand...

Replacing the MAF sensor assembly.
 
joegr said:
Replacing the MAF sensor assembly.
Click to expand...

Do these things go bad easily (haven't seen posts about this)?

Is it just a matter of picking up another and swapping it out and I assume the part is specific to the LS V8 (Gen2)?

Thanks!
 
lsintoronto said:
Do these things go bad easily (haven't seen posts about this)?
Click to expand...

I don't know. I don't recall any failures of the BAP inside the MAF. I know of several cases of the MAF sense wire getting dirty and causing problems, but that's not your issue.

lsintoronto said:
Is it just a matter of picking up another and swapping it out and I assume the part is specific to the LS V8 (Gen2)?

Thanks!
Click to expand...
Yes and AFAIK, yes.
 
joegr said:
My understanding (I don't have the emissions manuals, so I am not 100% certain) is that the LS does not have a MAP, but it does have a BAP built into the MAF. AFAIK, MAF systems require a BAP to avoid knock at high altitudes.

For the curious...

MAP = Manifold Absolute Pressure sensor.
BAP = Barometric Absolute Pressure sensor.
MAF = Mass Air Flow sensor.
Click to expand...

AFAIK....? What does that stand for?
 
So got a used MAF (was supposed to be working) and swapped it out and code came back again - bummed about that.
 
It could be the wiring or the PCM. You need to connect a Ford specific scan tool and read the sensor valves in real time to see what is going on.
 
I'm going to take a look at the EGR and the DPFE (on the LS the MAP/BARO function related to these I think?)

Anyone know where the DPFE is on an '04 LS8?
 
So, I got a new Motorcraft EGR valve (includes DPFE and EGR sensors) from Rock Auto and swapped it out and problem fixed. I guess it was the DPFE sensor that was bad and throwing the BARO code.

Thanks for the help!
 
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