P053F Code (Cold Start Fuel Pressure Performance) 2014 A4

[skinny1998]

I've got a 2014 A4 with 53.7k miles. Bought the car in Jan 2021 with 41k, no issues whatsoever until 52k miles

52.8k miles replaced high pressure fuel pump (went out on highway while outside temp was 100 degrees)
53.6k miles replaced PCV valve (replaced 11/04/22) also got an oil change

Just on the same tank of gas as when I replaced the PCV valve/oil and 170 miles later, I started my car this morning (snowed 5 inches overnight and a cold 20 degrees), rough idle cold start, was revving between 500-1500 rpms for a minute or so, a little black smoke came out right when I started it for 2-3 seconds, let it warm up and check engine light came on about 2 mins after it started. The rough idle went away after about 1 minute.

Drove it to autozone they ran the codes and got P053F Cold Start Fuel Pressure Performance.

Has anyone dealt with this or have an idea what it could be / if it's severe or costly? Really frustrated with all these issues all within the last 1k miles.

I don't drive the car hard whatsoever, stock, etc...

[Smac770]

Is this a CAE or CPM engine? If it is a CPM flex fuel engine, is premium or E85 in the tank currently?

[skinny1998]

Flex fuel AWD, I put in 91 premium (Colorado doesn't typically have 93)

[Smac770]

P053F is high pressure fuel line actual vs. high pressure fuel line specified difference is >2 MPa (20 bar). The "cold start" aspect is this check is performed 12 seconds after engine start during the high idle (cat heating active).

So either a problem with the high pressure fuel line pressure sensor or which the high pressure fuel pump. Or maybe a problem with the in-tank low pressure pump feeding sufficient fuel to the high pressure fuel pump. But part of that comes back to is it CAE or CPM.

[skinny1998]

Where would I find what it is (CAE or CPM)?

[Smac770]

Ok, so CPM engine, which means there is a fuel pressure sensor on the low pressure line. The CPM engine has a 5th injector on the low pressure line, but it's only necessary for cold start with Ethanol. The direct injectors can deliver the necessary fuel level with gas.

I'd start with logging the fuel pressure actual vs specified and see if the values imply anything. Is the actual jumping around, is it constantly low, etc. Check the alcohol % measuring value, is the engine thinking there's any appreciable Ethanol content to the fuel (is the fuel composition sensor working).

P053F, doesn't sound rare, I'm sure there are threads on it. I don't have any "oh yeah, it'll be this" to offer.

[Smac770]

The engine code is on the front of the engine, white sticker on the upper timing cover. But if it's flex fuel on the fuel door, then it's CPM. CAE is the gas only engine.

[skinny1998]

Got it, just ran out to my car and checked its Flex Fuel / 91

I spent some time trying to find some threads on it but none seemed to get the question answered.

Thanks for the input. I always get paranoid with my audi when stuff like this happens

[JLAllroad]

I suspect possible low voltage (battery) If this has only happened when cold, that would impact LPFP performance.

The high side has its own sensor and fault code, the hpfp is mechanical and houses the high side pressure regulator, was this replaced with OE Or Hitachi (OEM)?

You could also ensure the HP rail sensor and HPFP electrical connections are snug.

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[Smac770]

With the flex fuel engine, he has a low pressure fuel line pressure sensor G410. If he didn't get a DTC for that, the delivery pressure from the in-tank pump should be fine. But still worth logging all that and seeing how the values "look".

[skinny1998]

I’ll have to go out and check the battery. I’ve got a great independent mechanic that only does VW and Audi, however he’s booked out a few weeks.

I haven’t performed any maintenance on my car so am not sure what HPFP he put in it when that was fixed 1k miles ago.

Going to go start it now (was 8 degrees last night) and will keep you posted.

[skinny1998]

So turned my car on this morning. No issue with starting it check engine light did come on again. Let it run for a while and drove it to gym down the street. No issues.

After working out turned the car on (about an hour later) and the car turned on no problem and the Engine Light is NO LONGER there.

Seems like maybe the cold yesterday might’ve set off a sensor? Not sure if it’s worth taking to my mechanic or just driving it and see how it fairs.

[JLAllroad]

When scanning codes sometimes what come up and how it comes up is based on the scanner used. Additionally, some intermittent codes will not trip a cel where as others will based on severity. Let’s say yours was the latter but also intermittent, it will log the code but the cel will go away after a number of error free starts.

Certain scanners will give the freeze frame data of the where/when the code was logged.

All that said, in intermittent codes, I will often clear them and see what/if anything comes back.


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[Smac770]

At this point, probably sit on it and see how/if it returns. I always advocate VCDS (HEX-V2 cable is $200), but OBDeleven is cheap enough ($60) that everyone should have at least that for owning an Audi. You can read and clear codes on your own when you want, no driving anywhere. And it's a full vehicle aware tool, so reads more modules than a generic OBD-II scanner. And you can just leave it in the glove box so it's always with the car (VCDS runs on Windows; OBDeleven is an app that runs on Android and iOS).