2.0 TDI PD 16v Problems (BKD, BKP, BMN): An Owner's Guide

The 16-valve 2.0 TDI PD is a torquey, economical and generally hard-wearing engine that has covered enormous mileages in Golfs, A3s, Passats, Octavias and Leons. It also carries one failure that can destroy an engine with almost no warning - but, and this is the part most write-ups get wrong, only on some of the engine codes. On the versions fitted to the Passat B6 and the longitudinal Audis, the oil pump is driven off a balance shaft module through a small hexagonal shaft, and that hex can round off; oil pressure then disappears while the engine is still running happily. The Golf-class engines - AZV, BKD, BMN and their relatives - have no such module. They drive the oil pump by a chain straight off the crankshaft, much as the old 1.9 PD did, and they are not known for this failure. So the first job on any of these cars is to establish which engine you actually have. On all of them, a red oil pressure warning means stop and switch off, not "get it home". Everything else on the list - unit injectors (especially the 163 and 170 PS piezo versions), a sooted-up EGR system, sticking turbo vanes and a coked intake manifold flap - is ordinary diesel wear-and-tear by comparison.

Which cars got it, and how to tell which version you have

This is the PD (Pumpe Duse, or unit injector) 2.0 TDI, 16 valves, sold from roughly 2003 until the common-rail 2.0 TDI took over towards the end of the decade - the exact changeover date depends on the model and the market. Transversely mounted, it appeared in the Golf Mk5, Jetta, Touran, Passat B6, the Audi A3 8P, the Seat Leon, Altea and Toledo, and the Skoda Octavia II. Longitudinally, it went into the Audi A4 B7 and A6 C6.

Common engine codes include AZV (around 136 PS), BKD, BKP, BLB and BRE (around 140 PS), and BMN, BMR, BRD and BUY (around 163 to 170 PS), among others. Roughly speaking, AZV, BKD, BMN and BUY are the Golf-class engines; BKP, BMA, BMP and BMR went into the Passat B6; BLB, BRE, BRD and BPW into the longitudinal Audis. That grouping matters more than the power figure, because it is what decides how the oil pump is driven.

From 2005 VW also sold an 8-valve 2.0 TDI PD - BMM and its relatives - as a simpler, cheaper unit. It turns up where you might not expect it: the Eos and the Caddy 2.0 TDI 140, for example, generally got the 8-valve engine rather than a 16-valve one. Do not treat valve count as a shortcut for anything else, though. It does not tell you which oil pump drive you have: some 8-valve codes (BMP, BPW) use the balance shaft module, and some 16-valve codes (BKD, BMN) do not. Find the engine code.

• The three-letter engine code is usually on a sticker in the service book, often on a label under the bonnet or in the spare wheel well, and stamped on the block. On cars of this age the engine number printed on the V5C usually begins with those same three letters, but confirm it against the car rather than relying on the paperwork.
• A diagnostic scan will also read the engine code and ECU part number straight out of the engine control module - the quickest way to settle an argument with a seller.
• Whether a diesel particulate filter was fitted varies by model, market and year, so check the car in front of you rather than assuming.

Timing: this engine runs a cambelt, not a timing chain

The camshafts on every 2.0 TDI PD are driven by a toothed rubber cambelt. This is not a chain-driven engine, and there is no scenario in which you can skip the belt because "it's a chain". On this family the water pump is driven by that same belt, which is why the pump is normally replaced as part of the belt kit - worth confirming for your specific engine code with whoever does the work.

It is an interference engine. If the belt snaps or jumps teeth, the pistons meet the valves and you are looking at a cylinder head rebuild at best. The camshaft on a PD engine also operates the unit injectors, so the belt is under a heavier load than on an older diesel; VW revised belt kits, tensioners and intervals during production, and intervals differed by market. Do not take a figure off a forum - check the current schedule for your engine code and market, and if there is no dated invoice with a mileage on it, treat the belt as due.

There is drive gear down in the sump as well, and it causes endless confusion. On the engines that have a balance shaft module, the crankshaft drives that module - by a chain on the earlier units, by gears on later ones - and the module in turn drives the oil pump. On the engines without a module, the crankshaft drives the oil pump directly through a short chain. Neither arrangement is a cambelt substitute and neither is a routine service item, but on the balance shaft cars it is part of the assembly that fails, which is the next section.

The oil pump drive: which of these engines can lose oil pressure

On the versions built with a balance shaft module, the crankshaft drives the module bolted into the sump, and the module drives the oil pump through a hexagonal shaft sitting in a matching socket. That hex is small, and over time it and its socket wear and round off. Once the corners are gone the shaft spins without turning the pump, oil pressure collapses, and the engine keeps running until the bearings fail. From that point damage happens in a very short distance.

This is the part to get right before you spend any money. The module went into the engines VW used in the bigger and plusher cars - the Passat B6, the Audi A4 B7 and A6 C6 and their relatives - covering codes such as BKP, BMA, BMP, BMR, BLB, BRE, BRD, BPW and BNA, among a longer list, and the same arrangement carried on into the later common-rail 2.0 TDIs. The Golf-class engines - AZV, BKD, BMN, BUY - have no balance shafts and no hex drive; their oil pump is chain-driven from the crankshaft and does not have the same reputation. Because VW changed details through production and the code lists are long, confirm which arrangement your engine uses with a VAG specialist or a parts lookup against your engine code, rather than going on the badge, the body shape or a forum thread about a different car.

Where the module is fitted, this does not happen to every car - plenty have covered big mileages untouched - but the consequence is total, so treat it as the headline risk. VW revised the module and pump more than once during production, and the later specification is regarded as the better one. The repair is to replace the balance shaft module and the oil pump together with current-specification parts; it is a sump-off job, and on some cars there is a fair bit of dismantling to get there. It is not an afternoon on the drive.

Whichever drive your engine has, learn the difference between the two oil warnings. An amber warning about oil level is a top-up. A red oil pressure warning, usually with a buzzer and a stop message, is an instruction: pull over as soon as it is safe, switch the engine off, and have the car recovered. Restarting to move it a few more miles is exactly what turns a repair into a replacement engine.

• Early warning signs on a balance shaft car: a red oil pressure warning that appears only at hot idle or on a roundabout and then clears, a rattle or knock from the bottom of the engine, or metallic glitter in the oil or in the old filter at a service.
• If the car you are looking at is one of the affected codes, the single best question to ask the seller is whether the balance shaft module and oil pump have been replaced - and to see the invoice.
• On an affected car you intend to keep, having the module and pump changed pre-emptively with the latest parts is a legitimate option. Discuss it with a VAG specialist rather than a general garage, and do not pay anyone to do it on an engine that has no module in the first place.
• Correct oil and sensible service intervals matter on all of them. These engines want the PD-specific VW oil specification (505 01, or 507 00 where a particulate filter is fitted) - check your handbook for what your car calls for.

Injectors, especially on the 163 and 170

The PD design puts a unit injector in each cylinder, operated mechanically by the camshaft. The 136 and 140 PS engines use the earlier solenoid-operated unit injectors and are generally durable. The 163 and 170 PS versions - BMN, BMR, BRD and their relatives - use Siemens piezo unit injectors, VW's PPD system, and those are the known weak point of the family: they fail, they are expensive, and a badly failing one can over-fuel a cylinder, which in the worst cases has damaged pistons. It is still a fine engine to drive, but buy one on the basis that injectors are a when, not an if, and budget accordingly.

Symptoms of a failing injector are a cold-start rattle that does not settle, an uneven idle, a distinct knock from one part of the engine, smoke, misfire codes or worse economy than the car used to give. A failing piezo injector can also simply cut the engine out. A diagnostic scan showing the per-cylinder injection quantity deviation is the usual first check - one cylinder sitting well away from the others is a strong pointer.

Two related jobs are worth knowing about. The injector wiring inside the rocker cover can chafe and cause intermittent electrical faults that look like a dead injector. And the injector seals - the copper washer and O-rings - can leak, letting combustion gases and soot build carbon around the injector bore. Left long enough the injector can seize into the head, which turns a straightforward job into a much bigger one.

EGR, turbo vanes and the intake manifold flap

These three account for most of the everyday limp-mode and lost-power complaints on this engine, and none of them is an engine-killer.

The EGR valve and cooler clog with soot, particularly on cars used for short journeys. You get sluggish response, smoke, poor economy and eventually an insufficient-flow fault code and limp mode. Cleaning sometimes buys time; a clogged or leaking cooler needs replacing.

The turbocharger uses variable vanes, and soot and carbon can stick the vane mechanism or seize the actuator. The classic symptom is a strong pull that suddenly falls flat into limp mode part way up a gear, or lazy, breathless boost. Sometimes a clean and free-off sorts it; sometimes the turbo is finished.

The intake manifold cokes up with a mixture of oil mist and EGR soot, and the flap inside it and its linkage stick. That shows up as a shudder when you switch the engine off, rough running or a limp-mode fault. How that flap is actuated varies between engine codes, so have it looked at rather than assuming. Worth saying plainly: the famous broken plastic flap actuator and its P2015 code belong to the later common-rail 2.0 TDI, not to this PD engine - do not let a forum thread about a different generation drive the diagnosis.

One legal note: removing emissions equipment is not lawful for road use in the UK, and a missing particulate filter is a straightforward MOT failure on the visual check.

Other things worth knowing

None of these are reasons to avoid the engine, but they are the items that come up on higher-mileage examples.

Camshaft and follower wear is a real PD trait, because the camshaft drives the injectors as well as the valves and the contact loads are far higher than in an ordinary valvetrain. It is much more likely on a car run on the wrong oil or stretched intervals, and it shows up as noise, poor running and metal in the oil. If a camshaft is replaced, the followers go with it.

The tandem pump on the end of the cylinder head supplies fuel and provides vacuum for the brake servo. Its seals and diaphragm fail with age, which can leak oil down the back of the head, put fuel into the oil, or leave you with a hard brake pedal. A weak-feeling servo on a car of this age is worth investigating rather than living with.

Beyond that: dual-mass flywheels rattle as they age; the wet-clutch DSG fitted behind these diesels needs its fluid and filter service done on schedule; and on particulate-filter cars a life of short journeys leads to incomplete regenerations and a progressively blocked filter.

What to check on a test drive or pre-purchase inspection

Arrange to see the car properly cold. A warmed-up engine hides cold-start rattle, smoke and a slow-cranking glow plug problem, and a seller who insists on having it running when you arrive is telling you something.

• Find the engine code before you go, or at the car, and know from that whether it is one of the balance shaft module engines.
• Cold start: listen for a rattle that does not settle within a few seconds, and watch the exhaust for blue or heavy white smoke.
• Once fully hot, sit at idle with air-con on and watch the oil pressure warning. Any flicker at all is a walk-away until it has been investigated properly, on any version of this engine.
• Pull hard in third or fourth from low revs to near the limiter, twice. Watch for a sudden collapse of power into limp mode (turbo vanes) and for heavy smoke.
• Switch off at the end of the drive and feel for a shudder or shake - that points at the manifold flap.
• Check the oil level and condition, look for glitter on the dipstick, and look inside the filler cap. Look underneath for leaks around the sump and the back of the cylinder head.
• Ask for cambelt paperwork with a date and a mileage, for injector invoices, and on a balance shaft engine for any invoice covering the module or oil pump.
• Listen at idle with the clutch in and out for a dual-mass flywheel rattle, and on a DSG car check for clean, non-jerky low-speed shifts.
• Scan the car before money changes hands - see below.

The fault codes and live values it commonly throws

Most VAG tools show both a standard P-code and a five-digit VAG number. For the standard P0 codes the five-digit number is simply those four digits read as a decimal number plus 16384, so P0401 appears as 16785, P0299 as 16683 and P0234 as 16618. The ones you will meet most often on this engine are P0401 (EGR flow insufficient), P0299 and P0234 (under and over boost, usually turbo vanes or a boost leak), P0100 or P0101 (air mass sensor, which drifts as it ages and causes vague power loss), P0201 to P0204 (injector circuits), P0300 to P0304 (misfires) and glow plug faults such as P0380. Cars with a particulate filter add filter efficiency and soot loading codes.

Do not wait for a code where oil pressure is concerned. Depending on the car you may get a warning light and a buzzer with nothing useful stored at all. The warning is the fault.

The live values are more informative than the codes on this engine: per-cylinder injection quantity deviation, measured versus specified air mass at full load, actual versus specified boost, EGR duty and deviation, glow plug status, and on filter cars the calculated soot and ash load plus the distance since the last regeneration.

VAGPULSE - Windows software plus a cable, one payment - reads the car's modules, shows those live measuring blocks and the stored and pending codes, and handles coding and adaptations, which is exactly the information you want before buying one of these or before agreeing to a repair on your own.

Common questions