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TOP 10 VW Transporter issues reviewed. Part 1: Transporter T5 (2003–2009) - 1.9 TDI PD
Welcome to my first blog post covering the most common issues with T5 Transporters. I've sourced the top 10 lists from the internet, and added to them by showing which tests you can run on your van to find out if you have these issues.
I run health checks on customer vans at www.weluvdubs.com, a UK-based startup in the Midlands. I'm a VW enthusiast who works in IT by day, and I've developed a diagnostic tool that turns VW diagnostic data into more than a list of error codes and text that doesn't actually explain the issue or the steps to take. Customers get an easy to understand (but in-depth) report in traffic light style: green, amber and red show no sign of an issue, a mild warning or a critical issue respectively.
Our tests are categorised into tiers:
- TIER1 (CORE): A review of all module fault codes, run with the engine on (idle). We clear the codes and run the scan a second time to compare which codes return after clearing.
- TIER2 (PREMIUM): This includes a TIER1 scan, plus three short trips with the laptop plugged into the OBD port, logging the relevant sensors on each trip. The report is TIER1 plus an extra section on sensor data: which sensors are showing suspect data and what to do about it.
- TIER3 (COMPLETE): This includes TIER1 and TIER2, but goes more in depth with the sensor data. It's typically used when looking at a particular problem, such as an intermittent issue. We graph the sensor data and review the graphs afterwards to work out whether any of the sensors are pointing towards an issue.
As well as compiling a top 10 for each engine type, I've shown which tests can find out if your van has each issue. Alternatively, you can book one of our TIER1 to TIER3 scans to help pinpoint your van's issue(s).
Let's dive in to my top 10 Transporter T5 issues. I've created a list per engine type, counting down from 10 to the most common issue at number 1.
TOP 10 T5 ISSUES: T5 (2003–2009) · 1.9 TDI PD (AXB, BRR, BRS, AXC)
10. Oil and coolant leaks
WLD TIER1 TEST: Possible coolant level warning, but VCDS has very little reach here.
WLD TIER2 TEST: There are no VCDS checks we can run to identify oil or coolant leaks.
WLD TIER3 TEST: N/A
Overview: A visual inspection of the turbo oil lines, sump, water pump and hoses is a better test than VCDS.
9. Glow plug system and relay
WLD TIER1 TEST: Glow plug and relay codes will pick up issues. WLD TIER2 TEST: Glow plug output test; coolant temperature reading. WLD TIER3 TEST: N/A
Overview: A TIER1 test will show up the relevant fault codes, and a TIER2 test will back them up or highlight the particular area. We can't run a TIER3 test for this one.
8. Dual-mass flywheel and clutch judder
WLD TIER1 TEST: N/A
WLD TIER2 TEST: Clutch slip, rpm vs road speed, ABS wheel speeds.
WLD TIER3 TEST: Logged and charted rpm and speed on pull-away and uphill.
Overview: Judder may not flag a fault code (TIER1), although we would look for a wheel speed sensor failure as a potential cause.
We would run sensor data tests on clutch slip, rpm vs road speed and ABS wheel speeds to pick up the point when the judder happens (TIER2).
To take this a step further, we would graph the sensors tested in TIER2 (TIER3) and look at the graph data to pinpoint what happens when the vehicle judders. Disclaimer: VCDS only takes a few readings a second, so it won't catch the judder itself, but we would see trends like RPM spikes or clutch slip.
7. DPF blockage (where fitted)
WLD TIER1 TEST: DPF and differential pressure codes.
WLD TIER2 TEST: DPF status: soot load, differential pressure, distance since last regeneration.
WLD TIER3 TEST: Review of differential pressure under load.
Overview: DPF is quite a smooth one to check with VCDS, because the engine ECU keeps track of how full the filter is and when it last cleaned itself (a regeneration). A TIER1 test will show if the DPF has logged a fault. A TIER2 test tells us how much soot is in there and how long since the last regeneration, so we can catch a filter that's filling up before it puts the van into limp mode. In TIER3 we would watch the differential pressure (the pressure difference before and after the filter) under load, which shows how hard the engine is having to push through it.
Worth knowing: most 1.9 TDI T5s don't have a DPF at all, so check yours before worrying about this one. Vans that do short runs are the ones most likely to have problems, because the filter never gets hot enough to clean itself.
6. Turbo VNT vanes, N75, boost leaks
WLD TIER1 TEST: Charge pressure control positive or negative deviation (17963/17964).
WLD TIER2 TEST: Boost reading at idle and an N75 output test, where we watch and listen for the turbo actuator moving.
WLD TIER3 TEST: Requested vs actual boost, logged and charted on a pull in 3rd gear.
Overview: Turbo issues are where VCDS really earns its keep. A TIER1 test will show if the ECU has logged a boost deviation: positive means too much boost (often sticking vanes), negative means not enough (often a boost leak, the actuator or the N75 valve).
A TIER2 test confirms the actuator actually moves when we ask it to.
TIER3 is the best test for this one. We graph the boost the ECU asked for against the boost it actually got. If the actual line lags and then overshoots, the vanes are likely sticking. If it never reaches the requested line, there's likely a leak, and a split intercooler hose is a much cheaper fix than a new turbo, so it's worth knowing which one you've got before buying parts.
5. EGR valve sticking or clogging and intercooler gunk
WLD TIER1 TEST: EGR system and MAF (air mass) codes.
WLD TIER2 TEST: Air mass specified vs actual at idle; EGR output test. WLD TIER3 TEST: Air mass logged and charted on a full-load pull.
Overview: The EGR valve feeds some exhaust gas back into the intake, and over time soot mixed with oil mist gums it up. The ECU knows how much air it expects to see, and the MAF sensor tells it how much it's actually getting. In TIER2 we compare the two: if they're well apart, the EGR (or the MAF sensor itself) is the usual suspect. TIER3 does the same comparison under load, where a sticking EGR shows up best.
Intercooler gunk can't be seen by VCDS. Pull off an intercooler hose and look inside: a thin film of oil is normal, sludge or pooled oil isn't.
4. Tandem pump (fuel and vacuum) failure or leaks
WLD TIER1 TEST: Fuel supply related codes, although there often aren't any.
WLD TIER2 TEST: Fuel temperature and how steady the idle fuel quantity is.
WLD TIER3 TEST: Injection quantity logged under load, alongside boost.
Overview: The tandem pump does two jobs: it supplies fuel to the injectors and vacuum to the brake servo. VCDS can't measure either pressure directly on this engine, so this is a partial test at best. In TIER3, if the injection quantity maxes out and power drops while boost looks fine, that points towards a fuel supply problem.
For the vacuum side, try this at home: with the engine off, press the brake pedal a few times until it goes firm, then hold it down and start the engine. The pedal should drop slightly as the vacuum builds. If it doesn't, the servo isn't getting vacuum. Also look for diesel weeping around the pump on the end of the cylinder head.
3. Pumpe-Düse injector wear or failure
WLD TIER1 TEST: Injector valve circuit codes for each cylinder.
WLD TIER2 TEST: Per-cylinder fuel correction at warm idle ("smooth running" values).
WLD TIER3 TEST: Smoke and injection quantity under load.
Overview: This is one of the best things VCDS can do on a PD engine. At idle, the ECU adjusts the fuel to each cylinder to keep the engine running smoothly, and it shows us how much correction each one needs. A cylinder needing a lot more (or less) than the others is struggling. As a starting guide we rate within ±2 mg/stroke as green, ±2 to 3 as amber, and beyond ±3 as red.
One thing VCDS can't see is fuel in the oil. Check whether the oil level on the dipstick is creeping up, or the oil smells of diesel. That's serious, because diluted oil wears the camshaft, which brings us to number 2.
2. Camshaft and roller follower wear
WLD TIER1 TEST: Usually nothing until the wear is bad.
WLD TIER2 TEST: Per-cylinder fuel correction, the same test as the injectors.
WLD TIER3 TEST: Injection quantity vs boost on a full-load pull, to show a power shortfall.
Overview: On a PD engine the camshaft drives the injectors as well as the valves, which puts a huge load on the cam lobes, and the wrong oil makes it much worse (these engines need oil to VW 505.01). A worn lobe gives its cylinder a weaker injection stroke, so in TIER2 it can show up as one cylinder out of line, alongside low power in TIER3.
To be honest, VCDS gives clues here, not proof: the same reading can mean an injector problem. The only certain test is looking at the camshaft with the cam cover off. When buying, ask for the oil service history and the oil specification used.
1. Cambelt, tensioner and water pump service history
WLD TIER1 TEST: Cam/crank position codes if the belt has jumped a tooth. WLD TIER2 TEST: Cam/crank timing deviation at warm idle. Close to zero and steady is green, drifting towards the limit is amber, at or past the limit is red. WLD TIER3 TEST: N/A
Overview: This is number 1 because it's the most expensive one to get wrong. If the belt snaps, the valves hit the pistons and you're looking at a cylinder head job or a replacement engine.
VCDS can tell us if the timing has drifted, which points to a stretched belt or a worn tensioner, but it can't tell us how old the belt is. The most important test is the paperwork: the service book, the belt sticker under the bonnet, and an invoice showing the belt, tensioner and water pump were all done together. If there's no proof, budget for a belt change.
So what can VCDS actually tell you?
On the 1.9 TDI, VCDS can properly test five of the top 10 (injectors, turbo, EGR, DPF and glow plugs). It can give strong clues on four more (cambelt timing, camshaft wear, the tandem pump and clutch judder). The only one it can't help with at all is leaks, where a torch and a look underneath still wins.
A quick reminder: a health check isn't an MOT, and it doesn't replace a mechanic. What it does is tell you where to look, so you go to your garage with evidence rather than a guess, and you don't pay for parts you didn't need.
If you'd like us to run these tests on your van, you can book a TIER1, TIER2 or TIER3 health check at www.weluvdubs.com, or drop us an email at hello@weluvdubs.com.
Next up in Part 2: the 2.5 TDI, the five-cylinder engine in my own van, and arguably the one with the biggest reputation.