How much does an exhaust replacement cost?

How much does an exhaust replacement cost?

If you’ve noticed a change in the way your car sounds, a smell in the cabin or vibrations and rattles from under your car, there’s a good chance part or all of your exhaust system needs an overhaul.

It’s vital that you replace an exhaust system if it isn’t performing effectively. Not only can it affect the performance and efficiency of your car, but it can also have some serious health implications.

So, how much does it cost to repair part or all of your exhaust system  – and how do you know if it needs replacing?

How much is a new exhaust?

Made up of many different but equally important parts, the cost to replace an exhaust system will vary depending on your vehicle, the condition of the parts, and how they join together. Then there are also the labour costs to consider. 

Modern vehicles tend to use flanges with bolts as means of connection between sections. These can be troublesome if the parts have succumbed to excessive rust, sometimes resulting in the need to replace multiple parts at once. 

Cost Of Exhaust Replacement 

While this will vary based on your vehicle and the garage you choose, you can expect a replacement exhaust to cost between £300 to £600 depending on whether it is a smaller vehicle like a hatchback or a larger, luxury vehicle. This is for the parts and the labour involved. 

Luckily, it’s rare that an entire exhaust system will require replacing at once, it is usually the sections after the catalytic converter that are most susceptible to rust and damage.

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What parts make up an exhaust system?

For ease of manufacture, installation and repair, exhaust systems are made up of multiple components. Each of these exhaust parts varies greatly in cost to replace, depending on the type of car, the part in question and the state of corrosion under the vehicle. 

In order, from the engine to the rear bumper, the parts below make up your car's exhaust.

What is the exhaust manifold?

A manifold is a part that connects multiple routes for gases or liquids into one pipe. In this case, a car's exhaust manifold bolts to the side of the engine and routes the exhaust gases from each cylinder, into one pipe.

This pipe is often referred to as the Down-pipe, simply because it almost always runs straight down the side of the engine, to the underside of the car. 

If your car is turbocharged, the turbo will be mounted to the manifold/downpipe component, making removal more complex. There is likely also to be a Lambda sensor here, this measures the oxygen levels in the exhaust gases - useful for the engine's computer.

How much does it cost to repair an exhaust manifold leak?

Because the manifold is bolted to the engine, there are often quite a few components that need to be removed before it can be inspected or fixed. A replacement manifold, if the original one is leaking, would be moderately expensive as they are a complex and infrequently replaced part.

There is also a manifold gasket that seals between the manifold and engine block, these can break and need to be replaced, the part is cheap but replacing it can take a few hours.

Leaks at the bottom of the manifold between it and the flexi, cat or mid pipe (depending on the car) can be fairly reasonable to fix.

  • New Manifold Cost:  £300-£1,000
  • Manifold Gasket Cost:  £300-£400
  • Seal between manifold and rest of exhaust Cost:  £40-£150

Catalytic Converter

Many cars now have the catalytic converter built into the downpipe or at least the front section of the exhaust, that runs under the engine. Some cars also feature a secondary cat, somewhere along the midsection.

The catalytic converter contains materials such as Platinum and Palladium, which react with the exhaust gases to remove some of the harmful components. 

For this reason, catalytic converters are often the target of thieves, they can be worth hundreds of pounds in scrap.

How much does it cost to repair a catalytic converter?

The cost of a replacement OEM catalytic converter is between £600 and £1,000 while the cost of a type-approved catalytic converter replacement will be between £300 and £500.

Because the catalytic converter, or ‘cat',  contains exotic elements used to reduce harmful emissions, they are expensive to manufacture and therefore replace. Unfortunately, this has led to a trend of them being stolen from particular vehicles. 

An OEM (Original Equipment Manufacturer) cat will be more expensive than a generic off-the-shelf device, the issue is that the latter will take some degree of fabrication to install, instead of just bolting in. 

Aftermarket cats are also usually less effective at filtering emissions, although, as long as the new part is ‘type approved', it should not usually affect the MOT emissions test. 

Mid Section

As the name suggests, this is the middle section of the exhaust. In many cars, this will contain a silencer, resonator and secondary Lambda sensor.

The silencer simply baffles and reduces the sound of the escaping gases, and the latter removes high-pitched elements to the exhaust sound, without affecting the sound. 

The secondary Lambda is primarily to detect if the catalytic converter is doing its job, by monitoring the exhaust gases after they have passed through it.

Some luxury cars will have two silencers in this section, along with a resonator and a sensor, making it a large and heavy item.

How much does it cost to repair an exhaust mid-section?

  • Cost to replace Mid section: £300 - £500
  • Cost to replace Midsection (luxury car): £300 - £700

If your car is a high-performance or luxury model expect to pay slightly more, as the mid-pipe may contain extra silencer boxes, increasing the part cost.

This is where the age and complexity of the car can make a large difference, if the exhaust is overly rusty, and bolts cannot be undone, sections in front and behind the midsection may need to be replaced.

Diesel Particulate Filter

Found on all diesel vehicles from 2009 onwards, these are an extra filter that collects the soot that diesel engines produce. They are slightly different to normal exhaust silencers or catalytic converters in that they gradually fill up with deposits from the fumes. 

Regeneration cycles are run by the car's ECU, to heat up the exhaust enough to burn out the soot into ash. This would generally happen every 200-500 miles depending on the car. If the car is not driven for long periods of time, the DPF will clog.

How much does it cost to repair a clogged DPF?

You can expect to pay between £100-250 to clean and repair a DPF. Fixing a clogged DPF can be very expensive depending on what tools the garage has available. There are services that can clean a DPF of the built-up soot and allow it to be used again, sometimes though this is not possible

It will cost between £300-500 to replace a DPF.

Back Box

Underneath the rear bumper, the back box connects to the mid section and further reduces the sound level of the car's engine using baffling materials such as mineral wool. The back box also features the exit tip that is visible from the rear of the car.

Some vehicles, especially performance ones will have a box running the entire width of the car, with two exhaust tips for extra flow. 

How much is a new exhaust back box?

Replacing the exhaust back box will cost between £250-£600. This is another part that will vary depending on the type of car, on one hand, it has fewer flanged connections to become rusty, but it is also at the rear of the car near the wheels, meaning it gets splashed with road water, salt and mud. 

Exhaust Hangers, Sensors and Flexible sections

We’ve gone over the main exhaust sections, but there are other components that are essential for successful operation. 

The exhaust hangers are what attach the exhaust to the car. Because the engine vibrates significantly in use, the exhaust cannot be rigidly bolted to the car. Instead, rubber hangers are used in conjunction with steel brackets to suspend the exhaust system. 

As well as using rubber hangers to reduce vibration, flexible sections are often incorporated into exhausts, usually between the manifold/downpipe and mid-section. These are to allow for any movement engine to not cause strain on the exhaust sections.

As mentioned in the previous sections, there is likely to be one or more Lambda sensors on the exhaust system, these relay information about the engine's exhaust gases to the ECU via wires routed inside the car.

How much does it cost to replace a Lambda sensor?

Not only are the oxygen or ‘Lambda’ sensors complex, but they also have to survive harsh conditions under the car, being heated to over 300 degrees inside the exhaust. They can often fail through the vibrations and movement experienced by the cable that runs to the ECU.

When replacing a sensor, it’s usually best to go for a genuine part from the manufacturer, aftermarket ones tend to cause erroneous engine malfunction lights and will not last as long.

  • Replacement OEM Lambda sensor cost: £100 - £250

How much does it cost to replace an exhaust flexi pipe?

Replacing a new exhaust flexi pipe will cost between £120-£1000, from a small hatchback right up to luxury cars.

This stainless-steel tube, situated between your Oxygen Sensor and Catalytic Converter gives your exhaust line more flexibility when moving and helps to reduce the effect of vibrations on other parts of your engine. If it becomes cracked or broken, you may notice a decrease in engine power, a loud exhaust, or even a dragging exhaust pipe. A simple leak fix may only mean repair and labour costs but replacing a flexi pipe can become very costly.

How do you know if your exhaust needs replacing?

With so many parts of your exhaust to consider, there are a few different signs that a part of, or your entire exhaust system has a fault. Some of the most common signs that you need to replace your exhaust include:

  • Reduced fuel efficiency – Exhaust leaks can increase engine temperature and reduce efficiency meaning you use more fuel than usual
  • Reduced engine performance – Issues with your catalytic converter may reduce your acceleration power when driving
  • Noises, such as hissing, roaring or rattling parts - May be caused by leaks or loose parts
  • Vibrations – May be caused by a rusty exhaust pipe
  • Burning smell - Leaks in your exhaust system can release hot gases into the engine which can melt plastic parts and cause an unpleasant burning smell
  • Gas smell - Caused by leaks in your exhaust system
  • Check Engine Light – If your check engine light turns on, you should get to a garage as soon as possible
  • Rusting or sagging parts – You may notice rusting or sagging parts at the back of your vehicle

Is it illegal to drive with a broken exhaust?

It's actually illegal to drive with a broken exhaust system in the UK so we suggest you get it fixed as soon as it's possible! 

Will a broken exhaust fail an MOT?

If there's a major leak or there are unsafe emissions coming from your exhaust, then your car will fail its MOT. If it's just minor corrosion, then you will likely receive only an advisory note.

How important is it to fix your exhaust system?

Most of us are guilty of putting off car servicing and repairs to some degree, but your car's exhaust system is not something you should ignore.

At best, the fault with the exhaust will affect how the engine performs, often causing higher fuel consumption and less power output. Failing to repair some parts in a timely manner can cause much larger repair bills down the road. 

The main reason to repair your exhaust immediately is for your and your passengers’ health. Exhaust systems exit at the back of the car to keep the fumes away from occupants, leaks from any of the exhaust joints or components can easily cause dangerous gases to enter the cabin.

Furthermore, it might not be possible to detect when the fumes are entering, as you may become accustomed to the smell over time. 

Breathing in exhaust fumes can lead to headaches, sickness and fatigue. None of these are ideal whilst driving a vehicle.

You should always ask for advice from a mechanic if you’re unsure about what to do, find local garages near you with our garage search.

Think your exhausts may need replacing? Search for a local Bumper partner garage on our website and benefit from 0% interest and monthly payments on your exhaust repairs. Find out more about how 0% car repair loans work.


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