The B8 was released in model year 2008 A4’s as the successor to the B7 and continued in production until model year 2016. The B8’s came in sedan, avant/wagon, and allroad quatro (4-wheel drive) body types, with an additional A4L model for the Chinese market. In 2012 the B8 received a facelift which redesigned various exterior and interior features.
The primary engines used in the B8 A4 were the 2.0L TFSI and 1.8L TFSI for the non-diesel versions, and the 2.0L TDI for the diesel vehicles.
Overall, the B8 Audi A4 is a highly reliable vehicle. However, there are a number of common problems both engine and non-engine related in these vehicles.
B8 Audi A4 Common Problems
- Water Pump Failure
- Leaking Fuel Injectors / Failed Injectors
- Excessive Oil Consumption
- Faulty Power Steering Hose (causing speed wobble)
- Carbon Buildup in Intake Valves
1. Water Pump Failure
The water pump on the B8 A4 is the most vulnerable and likely failure point on these cars. The Genuine Audi factory water pump was manufactured with plastic, instead of aluminum. Over time, as the water pump is subject to high heat levels in the engine bay, the plastic housing can develop cracks, resulting in coolant leaking and the pump failing.
Additionally, the gasket between the water pump and the thermostat is another failure point. Gaskets naturally wear down over time and becomes brittle, breaking and deteriorating easily. As this happens, the gasket becomes susceptible to leaks as well.
The water pump has been known to fail up to 2 or 3 times prior to hitting 100,000 miles. This resulted in a class-action lawsuit relating to A4’s made from 2009-2014 with the 2.0L engine.
Sypmtoms of a Failing Water Pump – B8 Audi A4
- Coolant leaks around the water pump and housing
- Dripping coolant onto your garage floor
- Fault code for coolant / low coolant light
- Engine overheating (most tell-tale sign)
- Rust, corrosion, and build-up along the water pump
Water Pump Replacement Options
For those of you with 2013-2016 A4 model years, Audi issued a recall, so you could be in luck for a replacement if you haven’t had the recall fixed yet.
For all other model years, you should 100% replace your water pump with an aluminum water pump, instead of the OEM/Genuine Audi water pump. The aluminum part will prevent any housing cracks and is significantly stronger and less likely to fail than the plastic parts.
For those of you that want to DIY it, the repair is relatively easy, but will likely take 3-4 hours to complete.
Dealership/mechanic replacement cost: $600-$1,000 for the part plus labor
DIY replacement cost: $200-$250 plus 3-4 hours of work
DIY replacement guide: https://www.audizine.com/forum/showthread.php/578683-B8-A4-2-0-TFSI-DIY-Water-Pump-Replacement
2. Leaking / Clogged Fuel Injectors
The B8 A4 uses a direct injection system which uses fuel injectors to spray fuel directly into the engine cylinders. Over time, fuel injectors are prone to clogging, getting dirty, or leaking. The result of a bad fuel injector is not enough fuel being sprayed into the cylinders. Fortunately, it is not common for all of the injectors to go bad at once. These parts usually fail one at a time, but even one bad injector can cause significant performance and driveability problems.
When injectors fail, they can either get stuck open or stuck closed. This will cause either no fuel, or too much fuel to be sprayed into the cylinder. This can happen consistently, or sporadically and will likely result in frequent misfires.
Symptoms of Bad A4 Fuel Injectors
- Starting issues – difficult to start, slow starting, etc.
- Poor idling
- Engine misfires
- Engine fault codes (P0300, P0301, P0302, P0303, P0304)
- Loss of power
- Poor fuel mileage
- Gas dripping out of the bottom of the engine
Diagnosing Bad Fuel Injectors
A lot of these symptoms can also be created by bad spark plugs, ignition coils, a bad water pump, etc. Because injectors aren’t cheap and difficult to replace, you’ll want to check the fuel pressure at the fuel rail before you go replacing any of the injectors.
Guide on how to check or diagnose bad fuel injectors: https://www.audiworld.com/how-tos/a/audi-a4-b8-performance-diagnostic-guide-421897
3. Excessive Oil Consumption
Many B8 A4 owners have reported their car consuming an above normal amount of oil. This seems to be hit or miss for A4 owners, some report using 1 quart of oil every 1,000 or 2,000 miles, while some engines don’t have any issues at all.
In 2012 a class-action lawsuit was filed for 129,000 Audi’s for excessive fuel consumption. Audi initially determined that the problem was caused by an issue with the pistons and rings, but later found a fix with a new engine breather and a software upgrade. Along with the class-action lawsuit, Audi increased warranty coverage to 8yrs and 80,000 miles with an extended warranty of 1yr and 10,000 miles after the initial recall was fixed.
If you have excessive oil consumption, you can either continue to constantly re-fill the oil when it gets low, or take it in for the fix. Excessive consumption shouldn’t create any long-term reliability issues.
4. Faulty Power Steering Hose / Speed Wobble
A4 owners have reported speed wobble or excessive vibration while driving at both low and high speeds. Audi determined that the problem was frequently caused by a faulty power steering hose, and is more prone with owners who tend to hard-brake frequently.
This problem is more common in early model year B8’s. Audi issues Technical Service Bulletin TSB2020332/4 along with a recall to have the power steering hose replaced to correct this issue. While the hose might need to be replaced, sometimes this issue can be fixed by flushing and replacing the power steering fluid. Additionally, a speed wobble problem could be caused by poorly balanced wheels.
5. Carbon Buildup in Intake Valves
Generally all modern Audi engines use direct injection. Direct injection utilizes fuel injectors, one per cylinder, which spray fuel directly into the engine’s cylinders. In a non-direct injection engine, or one using port injection, the fuel is delivered through the intake valves, therefore there is a highly pressurized flow of fuel travelling through the valves, which keeps them clean and prevents gunk from building up.
Because the fuel is sprayed directly into the cylinders, there is no fuel going through the intake valves, and therefore, nothing to prevent the intake valves from getting gunked up from oil blow-back. The end result is a build-up of carbon deposits in the intake valve. As carbon deposits build up, air flow becomes restricted in the intake valve as it restricts the volume of air that can flow through it. This build-up and reduced air flow can result in:
Symptoms of A4 Carbon Buildup
- Decrease in performance / poor driveability
- Rough idling, engine stuttering, etc.
How to Clean Carbon Build-up in Audi’s
The most common and most effective way to reduce or clean carbon buildup in your Audi is through walnut blasting the intake valves. Walnut blasting takes crushed walnut pieces and blasts them through your intake valves with the use of compressed air. This process will blast away all of the carbon deposits and free up that extra space needed for maximum air flow.
Walnut blasting will require some special tools and takes approx. 4-6 hours. It’s not extremely easy even for an experienced DIY’er, so going to a mechanic is probably the best option. Audi dealerships typically charge ~$1,500 for the process, while you can find some indy shops who will do it for less than $1,000.
We recommend walnut blasting your engine every 50,000 miles or so.
B8 Audi A4 Reliability
Despite the problems mentioned above, the B8 A4 can be a reliable car with the proper care and maintenace. Most of the common issues above have been addressed and recalled by Audi, however the extended warranty on some of the problems like the water pump can be up for early model year B8’s. Overall, we’d probably score the car as “average” when it comes down to overall reliability, as problems become more likely and frequently as these cars continue to age.