The Mk5 Volkswagen GTI was the slam dunk that Volkswagen needed to bring the reviewers and buyers back to their hot hatch. Among the various updates was a new engine that used direct fuel injection and a high-pressure fuel pump. The improvements aided fuel economy and the engine’s power potential, but their freshness meant that the Mk5 had some teething issues. More than a few of those issues arose because of the high-pressure fuel pump system, including a fault with an attached sensor. Know as the thrust sensor, it reads fuel pressure and relays information back to the ECU when functioning properly. However, early sensors let fuel into their electronics, ruining their functionality. There were also problems with the pumps and their camshaft followers that could become catastrophic breakages.
Thrust sensor failures aren’t as common as they used to be but they do still hit owners every year. The sensor is mounted on the pump to read the incoming fuel pressure, telling the engine how much fuel is on the way. That all goes away when it fails, potentially leaving the owner stranded. The cam follower issue is the other big one, as it will deteriorate before disintegrating nearly completely, sending metallic bits through the valvetrain. Fortunately, replacing the thrust sensor, high-pressure fuel pump, and cam follower at home can be done with a handful of tools, a bit of patience, and a couple of hours' worth of work. Our MK5 Volkswagen GTI had a check engine light for those issues and Charles (HumbleMechanic) Sanville was kind enough to tackle the issue for all to see.
Symptoms of a failing High-Pressure Fuel Pump and Cam Follower:
- Momentary power cut under boost
- Engine has a "skipping" feeling
- Fuel Cut
- P0089, P0087, P1093, and/or P2293 Engine Code
The most common symptom of the issues revolves around sudden momentary drops in power, especially under boost. As the fuel system encounters mechanical or electrical faults, the engine's fuel supply is interrupted, causing drops in engine power. The dips might be far and few between early on, but they'll increase as components continue to deteriorate. At a certain point, the issues should also cause at least one of the codes listed above.
How long will it take to replace the High-Pressure Fuel Pump, Cam Follower, & Thrust Sensor on an Mk5 GTI?
The entire high-pressure fuel pump assembly is conveniently located a the top of the cylinder head, under the engine cover. The entire job should take you around an hour and a half with the right tools and some patience. The job does open the engine and expose critical components, so you will need to be careful while the pump is removed. You'll need to perform a significant amount of extra work if something falls in there.
How much will it cost to replace the High-Pressure Fuel Pump, Cam Follower, & Thrust Sensor on an Mk5 GTI?
The parts cost should total around $500 when everything is ordered. The fuel pumps aren't cheap, taking up the bulk of the required cost. Also, consider grabbing shop rags and parts cleaner. Everything you do while working on an engine is easier and safer when clean.
Tools required to replace your HPFP and Cam Follower:
Parts required to replace your HPFP and Cam Follower:
Steps required to replace your HPFP and Cam Follower:
Step 1: Remove Engine Cover
Start by disconnecting the electrical connector at the back of the cover. From there, remove the unlatch the retaining clip at the rear and pull the intake hose away from the cover. Then grab the cover on either side and wiggle while pulling the cover away from the engine.
Step 2: Bleed the High-Pressure Fuel Pump
With your safety glasses on (no one wants high-pressure fuel shot into their eyes) it's time to bleed the pressure from the fuel system. Disconnect the electrical connector at the top of the HPFP and then start the car. The car should run long enough for the pressure to bleed off. Then disconnect the thrust sensor on the left side of the pump and remove the dust cap to the Schrader valve.
Place your 13mm wrench on the Schrader valve, wrap it in a rag, and slowly loosen the valve. Once the pressure is out, place your rag lower to catch the remaining fuel and completely remove the valve.
Step 3: Remove the High-Pressure Fuel Pump
Begin by removing the fitting that holds the hard fuel line; it connects to the pump on the bottom. Use a 17mm wrench to remove the line from the pump. Take care not to knock the hoses or fittings around too much as they're fragile and have a tendency to break.
Next, using your T30 Torx socket, remove the three bolts fastening the HPFP in place, the rusty-looking ones in the image below. You should now be able to pull the pump off toward you, though, it might require some gentle persuasion by rocking back and forth. You should now have free access to the remaining hose holding the fuel pump in the engine bay. Remove the remaining hose and your HPFP should now be completely free.
Step 4: Remove and Replace the Cam Follower
You now have access to the cam follower with the high-pressure fuel pump removed. Although you can inspect it for damage, we recommend replacing it while you're in there. It's a cheap part that has a limited lifespan, so it makes sense as a "while I'm in there" fix.
Start by cleaning and lubricating the cam follower well (assembly lube or fresh motor oil is sufficient). Next, make sure the camshaft is aligned on the flat (flank) of the lobe. You do not want to be aligned with the peak (nose) of the cam lobe. This will require much more force to seat the HPFP.
After that, use a rag and parts cleaner to clean the area where the fuel pump sits. Then, apply some fresh oil or assembly lube to the flat portion of the cam follower and place it into the engine on the cam lobe.
Step 5: Install the new High-Pressure Fuel Pump and Thrust Sensor
Place the fuel pump into a vice, if you have one, and tighten the brass fittings. Torque the barbed fitting to 30Nm and the threaded fitting to 40Nm. Then fit the new pump onto the engine. Push the pump into position before threading the three retaining bolts in by hand. Then use a T30 Torx bit socket to drive in all three bolts as evenly as you can, and torque them to 10Nm.
Reattach the rubber line to the barbed fitting and refit the clamp. Then thread on the fuel hard line and tighten it up with a 17mm wrench, and do your best to torque it to 27Nm, or just about 20 lb-ft. Next, thread in the new thrust sensor and tighten it with a 24mm wrench. Finally, finish up the fuel pump prep by reinstalling the Schrader valve and tightening it with a 13mm wrench.
Wrap up the installation by reconnecting the two electrical connections and recapping the Schrader valve.
Step 6: Refit the engine cover
Place the engine cover into place on the engine and refit the intake. Clip it into place and then plug in the electrical connection.
After that, you can go ahead and clear any codes you have. Take your car on a long test drive and your check engine light (hopefully) won't return. These new components should last the remaining life of your car. Should they not for any reason, don't forget to make use of our Lifetime Replacement Guarantee. As always, follow along on our blog and subscribe to our YouTube channel for more great DIY and entertainment content.
Writer/Editor at FCP Euro and owner of a daily R53 MINI Cooper, a track-built R53 MINI, and a 1997 Dakar Yellow E36 M3 Sedan. ••• Instagram: @evan.madore