A rare Audi S5 with one of the brand’s naturally aspirated V8 engines has just changed hands for a fraction of what it originally cost, and the reason for the low price came down to a suspected engine problem.

The 2011 Audi S5 Coupé packs a 4.2-liter naturally aspirated V8 paired with a six-speed manual transmission. When new, the car cost more than £45,000 (about $60,000), making its eventual sale price of £2,700 (about $3,600) remarkably low. The car was bought by YouTuber Saving Salvage after an auction failed to meet its reserve. A Buy It Now listing was then posted, and he decided to take the chance. Once fees were added, the total cost came to just over £3,000 (about $4,000).

The S5 also had plenty going for it beyond its V8 and manual gearbox. It had covered around 90,000 miles, had two previous owners and came with its original book pack and two keys. The physical service book contained 13 Audi main-dealer stamps, with the first owner having kept the car for 14 years.

It was not a highly optioned example, though. The car had electric and heated front seats, cruise control and the standard CD-based audio system, but lacked features such as satellite navigation, Bluetooth media, DAB, a Bang & Olufsen sound system and a reversing camera.

The seller claimed a cylinder needed replacing

The low price made more sense once the engine fault became clear. The seller’s description claimed that “cylinder one needs replaced,” while the car itself was still able to run. However, it was showing multiple warning lights, including the engine management light, traction control warning and an electric parking brake fault.

The first diagnostic scan pointed toward cylinders three and four rather than cylinder one. There were also faults relating to the mass airflow and intake temperature sensor, which was found disconnected because the main air intake box was missing.

After clearing the codes, the engine management light returned with misfire faults for cylinders three and four. The inspection then moved to the ignition system. Some of the coil connectors were loose, and the coil on cylinder four was different from the others. The spark plugs also appeared relatively new, but several were wet with fuel.

That raised the possibility that the engine was receiving fuel but failing to burn it properly.

The engine proves it isn’t the problem

A compression test was carried out to determine whether the V8 had suffered the kind of internal engine failure suggested by the seller’s description.

Cylinder two produced around 180 PSI, giving a useful benchmark. Cylinder three also produced around 180 PSI, while cylinder four recorded more than 10 bar, putting it within an acceptable range. That was an important result because it did not point toward a dead cylinder or obvious mechanical failure.

The ignition components were then swapped around to see whether the misfire would follow a faulty coil or spark plug. After the connectors were properly secured, the issue affecting cylinder three disappeared, but cylinder four continued to misfire.

The team then confirmed that cylinder four had both a strong spark and fuel. That meant the search had to move further into the fuel system.

The upper intake manifold was removed, partly because the direct-injection V8 could potentially have significant carbon buildup. The injectors were then swapped between cylinders three and four. That test finally exposed the problem.

One leaking injector turns a scrap engine into a fixable Audi

Using a borescope while cranking the engine, the team found that the injector moved to cylinder three was stuck open and heavily leaking fuel. Instead of delivering fuel normally, it was continuously dripping into the cylinder. That excess fuel could flood the cylinder and wet the spark plug, explaining why the engine continued to misfire despite having good compression, fuel and spark.

It also explained why the original diagnosis did not make sense. The problem was not a cylinder that needed replacing or an obviously failed V8. The evidence pointed toward a faulty injector, with the misfire actually traced to cylinder four.

For a car bought for $3,600, that was a very different problem from needing a replacement engine.

The plan was to replace all eight injectors rather than only the failed unit, with the presenter estimating that they would cost a couple of hundred pounds each. A carbon clean was also planned while the intake was apart.

The diagnosis turned what initially looked like a potentially disastrous engine problem into a repairable fault on a rare V8 manual Audi. For a car that originally cost about $60,000, getting one for just over $4,000 including fees could prove to be an unusually cheap way into one of Audi’s naturally aspirated V8 manual cars.

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*Research for this article included AI assistance, with all final content reviewed by human editors.