Golf MK5 Turbo Problems

I thought I’d write something for the internet to find relating to a problem I had recently with my VW Golf MK 5.

It started 6-8 weeks ago with a heavy oil leak. It started as a drip under the centre of the car engine and quickly developed into loosing a litre every 300 miles. I got it in to a garage who diagnosed the actual turbo oil seals had gone so set about sorting that myself where I could.

It was new turbo time.

OEM costing £900+ I opted for a re-manufactured turbo. I did lots, and lots of internet research and ultimately found 95% of people were happy with a re-man and had no problems. So £300 lighter and I had a re-manufactured turbo.

It also cost £8 for the gasket set and a further £28 for the turbo oil feed pipe. Not happy with costing me enough, I then preventativey forked out £10 for an oil filter, and £28 for 5L of oil.

Already skint I then paid £150 to get it fitted. A new exhaust clamp was needed at the time (whilst the guy was working on the car) so there went another £10.

So that done the new turbo worked fine for 2 days. And then it ‘stopped’ working, and by that I mean there was no boost. Cars often go into ‘limp home’ mode which means you lose all boost and the car runs in a basic configuration to ‘get you home’. After checking all of the boost hoses and vacuum hoses I decided it must be either a MAP or MAF related problem. I highly doubted a new re-man turbo would fail after 30 miles.

After getting the car checked on VCDS it threw up the following errors;

  • 16622 – Manifold Pressure / Boost Sensor (G31) P0238 – 000 – Signal too High
  • 18000 – Altitude Sensor / Boost Pressure Sensor – P1592 – 000 – Implausible Correlation

It threw those errors despite having a known working MAP sensor, a new MAP sensor and my old MAP sensor. The MAP sensor (manifold absolute pressure sensor) measures pressure in the manifold and reports this to the ECU.

I then measured the output of the MAP sensor in VCDS and found it was reporting all sorts of boost even without the engine running. A multimeter confirmed there was a wiring fault somewhere. Below is the video of the boost pressure being measured in VCDS.

It turns out there is a VW Technical Bulletin about this which recommends the wire terminals are changed for gold plated ones. A quicker fix is to get a new MAP sensor wiring loom (around £21+VAT). A VW specialist can fit this for 2 hours labour +VAT. All in you’re looking at £145 to get it fixed. A new loom has to be hard-wired into the ECU which requires specialist tools, so needs a VW specialist to do it.

An expensive episode. £679 lighter.

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