Disclosure: This post may contain affiliate links, meaning when you click the links and make a purchase, we receive a commission. The Volkswagen/Audi TDI is an engine that was introduced in 2004 and used up until 2013 in Volkswagen, Audi, and Porsche vehicles. The engine features a V6 engine with a BorgWarner turbo and put out anywhere from 204-254 bhp & 332-406 lb-ft of torque depending on the version. We would like to say the is a reliable engine, but many drivers have found these engines difficult to make it past 100,000 miles without any issues. Just like any other engine, it does have a laundry list of issues. An interesting fact about the is that Audi built it from scratch and it has no relation to the V6 that was developed years prior by Volkswagen. Since this engine is in different applications and OEMs, PLEASE make sure the replacement parts we list below fit your vehicle before purchasing. VW Audi V6 TDI Common Problems are Applicable for: VW: Volkswagen Phaeton Volkswagen Touareg Audi/Porsche: (B7) A4 (B8) A4 Q7 (C6) A6 (D3) A8 Porsche Cayenne Timing Chain Tensioner (Pre 2007) Injector failure Glow Plugs Diesel Particulate Filter (DPF) and Sensors Clogged or Leaking Heater Core High-Pressure Fuel Pump Failure 1. Timing Chain Tensioner Failure – TDI A very common problem in early versions of the VW/Audi is failing timing chain tensioners. As the name states, the timing chain tensioner’s job is to maintain the proper tension of the timing belt so the belt can properly control the timing of the engine and drive the camshafts, oil pump, and balance shaft. Something interesting is that the earlier have 4 timing chains and two tensioners., whereas the older versions only have two. When either of the two tensioners fails, it could cause the timing of your engine to be off which could lead to pistons colliding with the valves. The timing chains themselves should never fail, but what ends up happening is a faulty tensioner that ruins the timing chain which in turn causes engine damage. If you have an earlier we would advise changing the whole set, chains, and tensioners, to ensure less probability of engine damage. Symptoms of Tensioner Failure: Engine stall or hesitate Engine won’t start Rough idle Rattling timing chain at 1500rpm Rattling timing chain at start TDI Timing Chain Tensioner Replacement Options: When it comes to replacing the timing chain or the tensioners, this is not an easy or cheap job. If you are looking to replace the right-side tensioner, you can do this without removing the engine itself. For the left side, you technically can do it without removing the engine, but you will have to remove the turbo. Unless you know your way around your engine, we would highly recommend taking it to a shop to put in a new kit. You will be looking at $2,000 – $3,000 depending on if engine damage has occurred. DIY Difficulty: Difficult 2. Faulty Fuel Injectors The VW/Audi engine uses common rail direct injection, which means fuel is sprayed into the cylinders, instead of the intake ports. With direct injection vehicles, like most of VWs and Audis, the fuel injectors can be problematic due to the engine’s conditions over time. The fuel injector’s responsibility is to pump diesel fuel into one of the 6 cylinders that the has. Diesel engines need fuel to pump at extreme pressures, which is why they need High-Pressure Fuel Pumps (we’ll discuss this a little later down the post). Injectors typically fail over time due to high heat and high-pressure levels constantly going through them. What will end up happening is one of two things: injectors will get clogged and eventually lead to failure or they will leak which will cause the cylinders to get less fuel than they need to. If the vehicle is maintained properly, you should only have to go through one or maybe two sets of injectors depending on how long the engine lasts. Symptoms of Fuel Injector Failure: Loss of power Engine misfires Rough idle Gas dripping from the engine Poor overall engine performance VW/Audi Fuel Injector Replacement Options: Replacing your fuel injectors is not the hardest DIY, but could be found difficult if you don’t know your way around the engine. Given the price of each injector, you can guess that it is going to be a costly repair. We would advise DIY if you can because it will save you some dough from labor costs. We would highly advise changing all injectors if you think just a few are bad because there’s no point in replacing 1 or 2 and having 1 fail in the next month. However, if you were looking to take it into a shop, you would be looking at a bill of ~$1,500. Buy Here: TDI Fuel Injector Replacement OEM DIY Difficulty: Intermediate 3. Glow Plug Failure Glow plugs are the next common problem and it is common in diesel engines. Each cylinder has its own glow plug, which glow plugs heat fuel and air to initiate fuel combustion to start your engine. Since glow plugs are heating elements, it may be difficult to start a diesel engine in the cold. Without several functioning glow plugs, your vehicle will not be able to start. When glow plugs fail, you will more than likely see an “Emissions Workshop” signal and Check Engine Light on your dash. Unless you have faulty glow plugs, you should only have to go through one or two sets of these throughout your vehicle’s lifetime because they SHOULD last up to 100,000 miles. Symptoms of Glow Plug Failure: Engine Starting issues – Slow or hard starting Rough idle White or black smoke emitting from the exhaust Engine misfires Engine light illuminating Glow Plug Replacement Options: Glow plugs are not too difficult to replace, in fact, it is probably one of the easier DIYs on this list. However, if you were looking to get these replaced at a shop, you would be looking at a bill of ~$400. Again, just like the injectors, we would advise changing all of them, so they are all brand new and shouldn’t have to run across this issue again. Buy Here: VW TDI Glow Plug Replacement DIY Difficulty: Easy 4. Clogged Diesel Particulate Filter (DPF) Another common problem in the is a clogged DPF. In any diesel vehicle, the DPF is important because, as the name says, it holds any leftover diesel particulate from going into the environment. Essentially, the goal of the DPF is to reduce emissions from diesel engines. As you can see from the picture above, a common failure of the DPF’s is carbon buildup, which will turn on a dpf light on the dashboard of the vehicle. There are two things you can do if the light comes on: drive at a speed of 80km – 100km (50mph – 62mph) at 2 – 2500 RPMs for a consistent 15 minutes max (or until the dpf light turns off) to burn off the excess soot or get it professionally cleaned. When the dpf light does come on, don’t take it lightly as this can cause serious engine damage if driven on for too long. With a clogged DPF, the vehicle will not be able to “breathe” properly and it vehicle will go into limp mode. This is something that should not be experienced more than once in your diesel engine. Symptoms of Clogged or Failing DPF: Poor engine performance (Limp-Mode) Poor fuel efficiency Rough start Strange engine smell DPF engine light illuminating Increase of black smoke out of the exhaust VW DPF Replacement Options: Depending on if you live in an emissions-strict place or not, there are three options you can do to replace, clean, or delete the DPF. Now we do not advise deleting the DPF, however, it is a cheaper option. If you were to replace the DPF with a delete kit or OEM part, it is a rather straightforward DIY. If you decide to take your vehicle to a shop to replace the DPF, you could be looking at spending ~$1,200. To get the DPF professionally cleaned, you would be looking at ~$350 – $500. Buy Here: VW/Audi TDI DPF OEM Replacement DIY Difficulty: Intermediate 5. Clogged or Leaking Heater Core This is a lesser common issue in Volkswagen or Audi TDI’s where cold weather is not prominent, but it is still common enough to include on this list. The heater core/auxiliary heater, essentially a radiator, is the component that radiates heat into the cabin. There are two main reasons why these fail, and that it is either clogged or it is leaking. When it does fail, the heat will not work in the cabin of your vehicle, and on very cold days, this isn’t fun to deal with. If you live in an area that gets cold often, you will probably go through more heater cores than someone that lives in a warmer area. These should last up to 10 years, but these are known to be faulty on VW vehicles, so this could vary. Symptoms of a Clogged or Failed Heater Core: No heat from your A/C Coolant levels low Wet floorboard from leaking coolant Sticky smell in your vehicle Heater Core Replacement Options: There are 2 options that you have with the heater core: you can try to flush it and hope that resolves the issue or you can replace it. The majority of the time you should just be able to flush it, which will save you some money, but if it is leaking you’ll want to replace it. The DIY can range from easy to intermediate depending on which route you decide to go. But if you were to take your vehicle to the shop, you’ll be looking at around ~$160 for flushing and ~$1,000 for replacing the heater core due to labor costs. Buy Here: Audi TDI Heater Core Replacement Buy Here: VW TDI Heater Core Replacement DIY Difficulty: Easy to Intermediate (Depending on flushing or replacing) 6. High-Pressure Fuel Pump (HPFP) Failure The HPFP failing may be one of the worst things that could happen to your engine. An HPFP’s job is to pump high-pressure fuel into the fuel injectors to make them function properly. When it does fail, it can pump fragments of metal through the fuel system, which means you will have to replace every component related to the fuel system except for the gas tank. The pump can fail in a couple of ways: something inside the pump comes apart and pushes metal scraps through the fuel system or the valve on top of the pump failing. If you’re taking care of your vehicle by using the proper diesel fuel, oil, and maintenance, you shouldn’t see too many of these pumps failing. This is what you don’t want to see in your HPFP. This means there are metal shavings in your fuel system. Photo Credit: HumbleMechanic. Symptoms of a failed HPFP: Limp or low-pressure mode Check Engine Light (CEL) illuminating (Fault Code P0087) High engine temperatures Low fuel pressure readings Poor engine performance Vehicle studdering while still or in acceleration Slow engine start HPFP Replacement Options: If your HPFP does happen to go bad, it will be an expensive fix for you. The first thing to do is to call your local VW/Audi dealer to see if it is covered under warranty because they have both extended the warranties regarding this issue. If you are covered, hallelujah, however, if you are not covered, you’re about to fork over some money. A big catastrophe would be to find metal scraps in your fuel system, pictured above, you are looking at anywhere from ~$10,000 – $14,000 depending on what all was affected. However, if they just need to replace the HPFP, then you’re looking at ~$1,500. Buy Here: VW OEM TDI High-Pressure Fuel Pump Replacement Buy Here: Audi OEM TDI High-Pressure Fuel Pump Replacement DIY Difficulty: Intermediate Volkswagen/Audi TDI Engine Reliability To conclude, these engines have mixed reviews when it comes to engine reliability. We would say the older versions are modified enough to be reliable engines, however, the earlier versions posed more problems. Some of them can make it to 200,000 miles, but likely won’t last much longer. Engine maintenance is crucial with these engines as most start having problems after 100,000 miles if not kept up properly.
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