# Got CEL P1488 today



## TDCruze (Sep 26, 2014)

So, on the way home from work and -16F outside, got my first CEL at 45k miles. P1488, supposedly a DPF pressure sensor issue. Everything seems to be tight and connected. Hoping it's a cold ask heck weather issue and will go away. 

I did notice my low pressure fuel system was running at 87 psi rather than the usual 60 psi, not sure if related or a concern?


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## Barry Allen (Apr 18, 2018)

The LP readings (if accurate) could point to fuel gelling.


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## TDCruze (Sep 26, 2014)

Barry Allen said:


> The LP readings (if accurate) could point to fuel gelling.


Other than the CEL and anomalous psi reading the engine started fine and was running smoothly. Never honestly experienced fuel gelling, so not sure? Always thought it caused issues with engine starting and running. I was thinking maybe ice in the pressure regulator. 

Put in heated garage for a bit, cleared the CEL. After restarting the engine the fuel pressure was back to normal and no issues after a short drive.


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## Barry Allen (Apr 18, 2018)

TDCruze said:


> no issues after a short drive.


Take it for a long drive to diagnose.

If you have high pressure readings from a system that flows through a filter of some kind of restriction, the indications point to the filter being restricted for some reason. With low temperatures, on obvious problem would be fuel gelling. The fuel filter in our cars has a heater, but I don't know how robust the heater is. If you have a cold enough temperature and you are driving at speeds enough to where wind chill can cool the filter, you might reach the point where fuel gelling can cause filter restrictions.


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## TDCruze (Sep 26, 2014)

Our arctic rated fuel "should" be good to -40 or below. Will have to put some more miles on here tomorrow. The car sat out all day in sub-zero weather so hard to say. Engine heaters were plugged in, but otherwise stone cold. 

Not sure where the low pressure fuel sensor is on the car? If its before or after the fuel filter?


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## Detrious (Jul 5, 2017)

There is a TSB for that code on the 2017 diesel models but with you having an 18 and 19 I would hope they had it corrected by then. Fix seems to be an ECM reprogram.


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## TDCruze (Sep 26, 2014)

Detrious said:


> There is a TSB for that code on the 2017 diesel models but with you having an 18 and 19 I would hope they had it corrected by then. Fix seems to be an ECM reprogram.


Ok thanks, I may have to look into that if the issue persists.


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## Barry Allen (Apr 18, 2018)

TDCruze said:


> Our arctic rated fuel "should" be good to -40 or below.


In the extreme cold areas of Canada I suspect most fuel is almost entirely #1 diesel, or a very heavy blend of it. I've only seen a few places in the USA with separate #1 diesel pumps - is that a widespread thing in Canada? For a -40º cloud point or CFPP, that would require the fuel to be almost 100% kerosene.

I don't know the setup or specifics of the heater in the fuel filter of our cars. I presume the heater is before the filter, so that the fuel is above the CFPP before it flows into the filter. If you have extreme cold conditions and there is enough frigid air flowing past the filter housing to cool it, I wonder if it's enough to chill the fuel to where it does cloud up again and perhaps contributes to some plugging of the filter? Or, if you already have some plugging of the filter, does the heater on the fuel line heat the fuel enough to get that plugging of the wax above the liquefaction point to melt all the wax?


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## TDCruze (Sep 26, 2014)

Barry Allen said:


> In the extreme cold areas of Canada I suspect most fuel is almost entirely #1 diesel, or a very heavy blend of it. I've only seen a few places in the USA with separate #1 diesel pumps - is that a widespread thing in Canada? For a -40º cloud point or CFPP, that would require the fuel to be almost 100% kerosene.
> 
> I don't know the setup or specifics of the heater in the fuel filter of our cars. I presume the heater is before the filter, so that the fuel is above the CFPP before it flows into the filter. If you have extreme cold conditions and there is enough frigid air flowing past the filter housing to cool it, I wonder if it's enough to chill the fuel to where it does cloud up again and perhaps contributes to some plugging of the filter? Or, if you already have some plugging of the filter, does the heater on the fuel line heat the fuel enough to get that plugging of the wax above the liquefaction point to melt all the wax?


Not sure about filter heater output or effectiveness?
Lines are all non insulated. I would imagine the fuel would cool back down after the filter quite a bit. 

I have never seen a #1 or #2 pump listed anywhere in Canada that I have been. They are just "diesel", premixed for the season.

North Dakota I have ran into #1 and #2 separate pumps and had to look up what to put in as it was winter and didn't want trouble.

The drive into work temps were still -18F, but was in heated 60F garage overnight. No, issues on the drive, fuel pressure normal at 60psi. Fingers crossed...


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## Barry Allen (Apr 18, 2018)

TDCruze said:


> Lines are all non insulated. I would imagine the fuel would cool back down after the filter quite a bit.


The filter is the point of the most troublesome restriction if you have gelled diesel fuel.

The fuel can still flow as a slush/gel through the lines and when it reaches the engine and is pumped into the fuel rail, heat from the engine will easily liquify it. As the fuel flows through the injectors, it will be liquid from waste engine heat - the fuel is used to cool the injectors and then the warmed fuel is pumped back to the fuel tank to dump there for cooling before it's pumped forward again.

If you have a completely cold-soaked engine and the fuel in the injectors is somewhat gelled, you can experience hard starts. The fuel will come out of the injectors in heavier globs than the fine mist that is expected. I've experienced this with one very cold day where I live. It was a long, hard start until the heat from compression and some misfires finally soaked into the tips of the injectors and then the fuel was injecting better. Was still a couple minutes of rough running until it was relatively smooth (though this engine is definitely loud in cold weather).

Same thing for fuel in the filter. You can have some restriction due to gelling but fuel will still flow (at higher pressures to force it through the filter media). If nothing is done to heat up the fuel with wax flakes floating in it, the filter will eventually plug up enough to stop the engine. That's why the fuel heater is helpful - the engine can start with fuel that is cloudy (partially gelled) and that heater will get the fuel flowing through the filter. In moderately cold weather the heater is probably enough to send fuel through the filter warmed enough to melt any accumulated wax.


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