How Much Does an Exhaust Backbox Repair Cost?

As the name suggests, an exhaust backbox is mounted at the back of the car and is the last component in the system. Like all exhaust components, they are subject to lots of road salt, moisture and debris, so they often rust out over time. 

Read on for more information on how much they are likely to cost, and how to know if your car's exhaust backbox needs replacing.

How much is an exhaust backbox to repair?

The cost of an exhaust backbox repair will range from £150 to £1,500, depending on the type of car. Other factors, such as system configuration (some cars don’t have a separate back box) and parts availability, affect the cost.

Below are the prices across some ranges of vehicle types:

• Small hatchback/city car exhaust backbox cost: £150-200

• Family hatchback exhaust backbox cost: £220 - £350

• Large car/SUV exhaust backbox cost: £230 - £420

• Performance car exhaust backbox repair cost: £520 - £1,800

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What is an exhaust back box?

The back box is generally the very last silencer in the exhaust system; its job is to quieten down the exhaust noise before it exits the vehicle at the back.

Exhaust silencers work by absorbing the energy of the pressure (sound) waves caused by the engine's combustion. They do this by forcing the gases through packing material such as metal or mineral wools. 

Another technique is to cause the sound waves to diffuse by routing them through chambers and perforated tubes that slow down and modify the pressure pulses, reducing the overall volume. 

How to tell if my backbox needs replacing

The first sign of any damaged exhaust component is likely to be the noise. If your car is suddenly much louder than normal, or you can hear a slight puffing or chugging noise when walking around it whilst idling, it’s likely your exhaust is leaking somewhere.

Without getting under the car, it’s going to be very difficult to tell where the leak is coming from exactly, but the most common places to go are the joints between the piping and a silencer, such as the back box. 

For a quick and simple check of your back box, have a peek under the rear of the car (with the engine off) and look for obvious signs of rust, which will show as a light or dark orange colour. 

Pay close attention to the front of the back box - which is likely to be roughly inline with the rear wheels. Note any damage or separation of the metal skin of the back box – these are all signs the part needs to be replaced. 

Can I drive with a damaged backbox?

You should not drive with a leaking exhaust, regardless of where the leak is, it should be repaired as soon as possible to avoid more damage occurring.

Not only is the noise likely to be distracting and anti-social, the exhaust fumes could easily enter the vehicle, which can cause dizziness, nausea and loss of consciousness. It can also cause error messages from erroneous sensor readings. 

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