P310B / 012555 for Audi A4 2.0T

Since this comes up a lot, figured I'm make a forum post on the subject so future searches can find it....

The B7 Audi A4s with the 2.0T have a very common issue with the following DTC:

P310B/012555 - Low Pressure Fuel regulation: Fuel Pressure Outside Specification

Most of the time this is caused by a failing lift pump in the fuel tank. The lift pump is run via a duty cycle, in other words, it isn't "powered on" when the engine is running, but rather cycled on and off at a very fast rate, like a strobe light. With the engine at operating temp, the duty cycle of the lift pump should be around 50%. You can view this by the following:

Start VCDS
[Select]
[01-Engine]
[Meas Blocks - 08]
Group 106, field #2

I would want to see that reading below 55% at idle, the closer to 50%, the better. If the reading is greater than 60% at idle, then you have problems. The lift pump is working harder than it should. So if you then try to do burn outs in your neighbor's lawn, a lift pump that is overworked at idle is not able to keep up when heavy fuel demands are called for, the lift pump in the fuel tank just can't keep up.

First I would verify there are no kinks or damage with the fuel lines for the low side fuel pressure, from the fuel tank up to the engine bay. If a fuel line or hose is restricted, that will cause the lift pump to work harder.

If the fuel lines all check out, I would next see about replacing the fuel filter. If the filter is gummed up, again, that can make the lift pump work harder to overcome the restriction. To this end, there are different versions of the fuel filters because they have fuel pressure regulators integrated into the filter itself. We have had several cases of people getting the wrong fuel filter, every time, the filter was not purchased from the dealer. I would suggest getting the filter from the dealer. IMHO, if the fuel filter has 80,000 miles (130,000 km) on it, it has done its job, replace it anyway.

Last, and most likely, the lift pump in the fuel tank is bad. A common mistake we see people make when replacing the lift pump is not getting the part from the Audi dealer. I have seen many cases were the original factory installed lift pump had failed and the duty cycle was say 70% at idle, and then a non dealer supplied lift pump was put in and it would run at 85% duty cycle, worse than original. Be warned, there are places that will sell you "factory parts" that come in the "factory box", but they are not same quality as you will get from the Audi dealer parts department. Or we get a shop calling us up saying they've replaced the lift pump 6 months ago and it has failed again..... it isn't a dealer supplied lift pump. We get this example 2 or 3 times per week and that is really the whole point of this post... get the lift pump from the dealer.

Enjoy.

Jef your post is great with the exception it attacks the industry you work in.....and for the most part I agree.

Not all outside parts suppliers sell crap or clone OEM parts.....
Franchise parts departments or service, should not be put on some type of moral high road pedestal.

For that matter, believe it or not Jef.......... many dealers will outsource their own parts through an AFT supplier, if the sale is not under warranty...... to hit higher profit #s.

Hence, why GAI, Votex, WAWD.....all gone now...... was born from many years ago, of groups of franchises collectively buying overseas.
It still happens to this day.

Just because a part is bought at a franchise........ doesn't mean it is always genuine..........nor does it mean it came form the actual VW/Audi depot.

VW on many occasions depending on importer and exporter............ will stick it, to their own dealer network.

Hence why importers started importing parts from the vendors directly............ rather than through VWoA or historically Worldwide..

Example:
I bought these pumps direct from VWAG here below and they are genuine in the pallet cask......they are cheaper because so, and they are Made in Germany.
They come in no box some #s do.
It's what's known in the industry as mechanics packs, like when you can buy filters in a case verse individual boxes.

http://www.ebay.com/itm/VW-Genuine-...19-051M-/330844804305?ssPageName=STRK:MESE:IT

Example of how VW dumps product on aftermarket and drops retail. So yes it is possible.............

http://www.vwparts.com/parts-outlet-center/

If people stuck to that rule you stated, than everyone would use an ODIS sub with VAS tester and not VCDS.
We both know that isn't going to happen, because VCDS hits the price point, and delivers a superior product for said point!
I think maybe say buy parts from people which care where they source, and deliver their parts from.......... with a valid reputation.


Just keep In mind the duty cycle being higher with a replacement pump, is not always an indication that the pump is faulty.
Some vendors have assembled higher volume pumps, which produce more fuel flow at a higher draw rate.

See.......... the aftermarket can come up with a solution........
The OEM will stick to their guns that there is no issue for design, because that would admit liability. You know........ kind of like when you sold a extractor tool for coil overlay harnesses or that the OEM just sells the same crummy overlay harness with no ground strap to battery with the bonded chemical crimp.

The draw is a guide,........... it should not be relied on as the only indication that the lift pump is not working correctly.

Tests for volume and PSI are what are required in order to verify.......... not just a block value.
I agree there is an issue in the industry for clones for everything.

Helpful understanding of design.....and since these cars are so popular for mods.....The bold should be adhered too.

Modern electric fuel pumps are “Positive Displacement” type pumps, this means that the pump cannot produce pressure unless it is acting upon a restriction. The only “restriction” in the system should be the fuel pressure regulator. The regulator controls the system pressure; the pressure ability or flow volume capacity of the fuel pump will not alter the system pressure.

Due to the high pressure and volume requirements placed upon these pumps, manufacturing tolerances are extremely fine. Motor speeds can be as high as 10,000 RPM and the clearances within the pumping elements down to microns. Cleanliness of the fuel system is vital, with an efficient high quality filter an essential part of the fuel system.

Specification Details.

Fuel pump specifications are given in relation to their engineering design specification. Hence the flow rates quoted are for the operating pressure and flow rate required to suit Original Equipment requirements. The specification guarantees the flow rate at the specified pressure or less. Whilst reduction of pressure will increase flow slightly, manufacturing tolerances between pumps differ and hence we do not specify exact flow rates at pressures other than those stated here.

Power Ratings of Fuel Pumps. [Horsepower]

It has become an aftermarket performance industry practice to rate fuel pumps in relation to expected engine power outputs, mainly Horsepower.

As this method of measurement has many issues in relation to various calculation methods, accuracy, individual interpretation and overall relevance, Bosch as an Original Equipment supplier of fuel pumps, does not subscribe to this specification method.

The major design requirements of vehicle manufacturers of any type of pump is to provide a specified flow volume at a specified pressure, therefore manufacturing standard engineering measurements will only be used.

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