Ultimate Audi B8 RS5 Guide

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The B8 RS5 was the first-generation (2011-2015) of the Audi RS5 and it was introduced in 2011 and is still in production today. For those that are new, the RS5 is our attainable dream car. One day we’ll build an insane RS5 and remember this sentence. Anyways, the RS5 is the highest-performance variant of the Audi A5. The B8 RS5 had two body styles: coupe and a cabriolet (convertible). It received a facelift for the 2013 model year and it competes with the likes of Jaguar’s XKR, Maserati’s Granturismo, and the Lexus RCF. The B8 RS5 came equipped with a NA 4.2-liter V8 engine and a 7-speed S-Tronic automatic transmission. We honestly prefer the newer 2.9L twin-turbo found in the B9 RS5, but still love a good-sounding V8. Check below for the V8 engine specs.

If you are wanting more specs in the table above, let us know in the comments and we will gladly add on to the table.

Audi B8 RS5 Dimensions

In this section, we will be going over the interior and exterior specs for both the coupe and cabriolet versions of the B8 RS5.

As you can see, there aren’t many differences between the coupe and cabriolet model. Only things that are different are curb weight, height, and cargo space, mainly due to the convertible.

Audi B8 RS5 Pricing

In this portion, we’ll be covering new and used prices for the Audi B8 S5. A 2015 B8 RS5 retailed for $70,900. Now on the used side, depending on what year and mileage, an Audi B8 RS5 can range anywhere from $27,585 – $52,500 for an average price of $40,042.50. Many question if a B8 RS5 is worth it at the used prices it’s still sitting at and we are all for it. Now onto the common problems of the B8 RS5 to assist those that are looking into getting a used one or those that already own one.

The 5 Most Common Audi B8 RS5 Engine Problems

1. Faulty mechatronic unit
2. Carbon buildup
3. Subpar brakes and rotors
4. Cracking coolant lines
5. Suspension bushing wear

1. Faulty Mechatronic Unit

This was a common and serious fault in 2013 RS5’s and essentially there is a faulty circuit board within the mechatronic unit. A mechatronic unit is the control center of a vehicle’s gearbox. This issue was so common in the early B8 RS5’s that Audi issued Technical Service Bulletin (TSB) 2030477 to address it. From a technical standpoint, essentially what can happen is oil additives come in contact with the circuit board in the mechatronic unit which causes contact loss with the circuit board. If your vehicle is experiencing this issue a message that reads “Gearbox malfunction: you can continue driving” in the cluster of the vehicle. As it reads, you CAN continue driving, but it would be highly advised to take the car in ASAP.

Symptoms of a Faulty Mechatronic Unit:

• No power in reverse
• Error message with any of these DTC fault codes:
  • P17D8
  • P0726
  • P174B
  • P174F
  • P179C
  • P179D
  • P174C
  • P174A
  • P174E
  • P1740
• Gears getting stuck
• Limp mode engaged
• Jerking or choppy shifts

Mechatronic Unit Replacement Options:

When it comes to a failing mechatronic unit, there are two options you can do: repair or replace it. We would suggest repairing it because it would save you money, we’re talking thousands. There are repair kits, like the one below, that is a fraction of the cost of a new mechatronic unit. The repair kit isn’t cheap either, so don’t blindly buy it thinking this is the exact solution. If you don’t have the proper tools, this is a rather difficult DIY. And if you were to take it into the shop for this repair you would be looking at a bill of around $1,500 – $4,000.

Audi B8 RS5 Mechatronics Repair Kit

DIY Difficulty: Intermediate

2. Carbon Buildup

Carbon buildup is a very common problem on most direct injection engines and the 4.2L V8 is no exception. Direct injection in an engine means fuel is pumped directly into the engine’s cylinders via the fuel injectors. Over time, this can cause the intake valves to be clogged with carbon or soot. When buildup of carbon occurs in the intake valves, engine performance can noticeably be dampened. Imagine breathing your nose. It is more difficult to breathe through your nose when congested versus not congested. That’s essentially what is happening in an engine when carbon buildup takes place.

For starters, this is normal, we just want to reiterate this fact. As a good rule of thumb, you will want to check out your intake valves every 30,000 miles. It is possible to manually clean the intake valves yourself if you catch it soon enough or have the proper tools. However, if your B8 RS5 has 60,000 miles and the intake valves have yet to be cleaned, it may be time to clean them manually or have them professionally cleaned. Many people claim they have not noticed any difference between clear or clogged intake valves. However, every time we have had this cleaning service, on multiple vehicles, it has made a huge difference in the engine’s performance.

Symptoms of Carbon Buildup:

• Engine misfires
• Poor idle
• Black smoke coming out of the exhaust
• Rough engine performance
• Irregular slow acceleration
• Harsh cold and warm starts
• Decreased fuel efficiency

Ways to Prevent Carbon Buildup:

• Replace ignition coils, spark plugs, and injectors regularly
• Change your oil and filter regularly, if not more than normal
• Use high-quality fuel, preferably at or over 93 octane
• Drive on the highway at high rpm’s for 20-30 minutes every once in a while
• Manually inspect the valves or ports every 30,000 miles and clean if needed
• Get the valves or ports professionally walnut blasted every 60,000 miles

3. Subpar Brakes and Rotors

This isn’t necessarily a “common problem” so to say, but we have read about this many times so figured we would touch on it. For some reason, the brakes and rotors on the B8 RS5 are very subpar for being the highest-performance model you can get of the Audi A5. For those unaware, subpar means below the average level. When we say subpar, we specifically are talking about normal wear and tear. It seems like the common thought here is Audi cheaped out on the rotors and brake pads. The factory rotors and brakes wear at a faster rate than they should.

When purchasing a high-performance sports vehicle, you would expect the highest quality of performance parts. If you own a B8 RS5 and haven’t changed your brakes or rotors with over 60,000 miles, we would advise doing so. Normally, brakes and rotors would need to be changed just once in a vehicle’s lifecycle.

Symptoms of Brakes or Rotors Wearing:

• Brake light illuminating
• Squealing or squeaking while braking
• Soft or spongy brakes
• Vehicle vibrating or wobbling while braking
• Metal grinding noise while braking (worst case)

Brakes and Rotors Replacement Options:

When you are experiencing any of the symptoms above, we would advise getting your brakes checked out ASAP. It is very hazardous to drive with bad brakes. If you end up having to replace your brakes and rotors on your B8 RS5, go the aftermarket route. Although they may be more expensive, they will last much longer and perform better. With proper tools, replacing the brake pads and rotors is not terribly difficult. If you are needing to take it to a shop, the bill will be costly, but mainly due to the cost of parts.

DIY Difficulty: Intermediate

4. Cracking Coolant Lines

The coolant lines we’re specifically referring to here are the coolant lines to the overflow tank. Coolant lines are used to circulate coolant through the engine. There are two coolant lines, or hoses, that go to the overflow tank, #8K0121086AA or #8K0121081BA. These are plastic and are prone to cracking due to the extreme temperatures found in engines. People are seeing these crack at the barb fitting or completely break off from the radiator fitting. We have seen many B8 RS5 owners claim that they have had multiple coolant hoses crack over the lifespan of the vehicle.

Symptoms of Coolant Lines Cracking:

• Coolant light illuminating
• Irregular coolant loss
• Engine overheating
• Sweet smell coming from the engine bay
• Coolant puddle underneath the vehicle
• Steam coming from under the hood

Coolant Line Replacement Options:

If you find yourself experiencing any of the above symptoms, it is likely the expansion tank vent hose is cracked or a failing water pump/thermostat. If you’re lucky, it is just the hose because it is an inexpensive part and doesn’t take long to DIY. To get this hose replaced at a shop, you will likely be paying $300 – $400. If you own a B8 RS5, it might be a good idea to keep the two parts below on hand as it seems that these cracking is a semi regular occurence.

B8 RS5 Expansion Tank Vent Hose
B8 RS5 Engine Coolant Overflow Hose

DIY Difficulty: Easy

5. Control Arm Bushing Wear

Not the biggest deal, but definitely worth mentioning is the bushings on the front suspension tend to wear faster than normal. Kind of like the brakes and rotors, the bushings seem to be the same issue. Although small parts in size, bushings actually play a big role in a vehicle’s suspension. A bushing is a cushion that absorbs road bumps, controls the amount of movement in the suspension joints, and reduces road noise. There have been many customers having to replace bushings more than once in the Audi B8 RS5. Typically, you will likely have to replace the bushings or control arms at least once in a vehicle’s lifecycle. However, it seems like it may be more than that on this car.

Symptoms of Bushing Wear or Failure:

• Vibrating steering wheel
• Clunking or banging sounds coming from the suspension when hitting bumps in the road
• Wandering steering
• Uneven tire wear or blown tires
• Decrease in brake efficiency

Replacing the bushings can be a tricky DIY if you aren’t sure where they are located. Here is an excellent forum and video to assist if you go the DIY route. We have seen customers get quoted $2,500 from the dealership to replace all the bushings, which is overpriced. However, if you are looking to take it to a local shop, expect somewhere around $1,500 for all the bushings.

Audi B8 RS5 Mods

Now that we’ve covered the common problems, let’s jump into the fun part, mods. Since it is a naturally-aspirated engine, it’s a little more difficult to add mods and see huge performance gains. However, we will lift our 5 favorite mods when it comes to modding out the B8 RS5. With all of the supporting mods and proper tunes listed below, a B8 RS5 could push a whopping 400whp. Now, if you are looking for more power out of your V8, there are some enthusiasts that have spent a lot of money on a turbocharger or supercharger that can push the B8 RS5 up to 800CHP (Crank Horsepower).

1. ECU Tune (JHM)
2. Upgraded Intakes
3. Downpipes
4. Catback Exhaust
5. Coilover Kit
6. RMR Transmission Cooler

If you happen to have a modded B8 RS5, let us know what you have done in the comments below!

Audi B8 RS5 Reliability

Is the Audi B8 RS5 reliable? We’ve been perusing the internet via forums and reddit, and have come to the decision that the Audi B8 RS5 is very reliable. The 4.2L V8 engine is essentially an R8 engine that has been stripped of two cylinders. So essentially the internals of the engine have been over-engineered for this car, which is a great thing for the consumer. Something worth mentioning is that the repairs and maintenance are not cheap on this vehicle and engine. But, if maintained properly, the Audi B8 RS5 is pretty bulletproof.