Td5 Specialists — Parts, Tuning & Diagnostics

Probably the most common issue as it can cause varying issues.  Oil creeps up past the TD5 injector loom to the red ECU plug which then interferes with the electrical signals.  The actual issues you might see vary considerably, but most commonly it will cause rough running/idle.

The quickest fix is replacing the injector loom and cleaning the red plug with contact cleaner, the best long term fix is using a good quality loom and 5w40 engine oil meeting VW 505.01 which is designed for PD type engines (low conductivity).

This is an all year round issue but tends to present itself more commonly when the weather starts turning colder.

Common causes:

• in-tank fuel pump failing
• air bleed valve in fuel filter housing
• injector seals (copper washers)

All relatively straightforward fixes.

This can seem quite an alarming issue to the new Td5 owner, the engine is overboosting.  Common causes are split intercooler hoses, faulty wastegate modulator, wastegate modulator pivot seized, faulty airflow or MAP sensor.

Oddly there are only a few reasons the Td5 engine management light (EML) will come on:

• faulty throttle pedal
• faulty crankshaft position sensor
• over-boost

An engine rattle when the clutch is up, which goes away when the clutch is engaged, can often be signs of a failing dual mass flywheel.

The Td5 fuel pumps have high and low pressure, when the high pressure side is failing/failed there simply is not enough fuel to get past the mid rev range.  This can also be a sign of a failing fuel pressure regulator so check both before replacing anything.

If you have a Td5 with a high or rising oil level this needs to be dealt with quickly.  If the oil level rises too much there is the potential for the engine to runaway on itself, not to mention how diluted/thin it will be.

This is caused by failed O rings on the injectors allowing diesel to escape into the cylinder head.

Most commonly a squealing sound when accelerating is caused by a warped exhaust manifold or failed exhaust manifold gasket.  Left unfixed this can lead to exhaust studs being broken.

If your Td5 cuts out and won't restart AND the engine management light is on then check the fuel shut off switch on the bulkhead in the engine bay.

By design the fuel shut off switch triggers in the even of a collision.  In reality this can happen for no reason at all.  Save your self a lot of time diagnosing issues that don't exist and check this switch first!