Car Undertray Repair Cost

If your car’s undertray is damaged and is either sagging or has been flagged on an MOT, it’s important to get it sorted ASAP. It provides a vital service, protecting the lifespan of many other components.

This guide will discuss the costs of undertray repair and how best to approach it.

How much does it cost to repair an undertray?

Replacing an undertray costs between £150 and £600, depending on the car and the amount of damage sustained.

If your undertray is damaged but can be repaired, expect to pay between £30 and £100 for this quick fix.

As the prices stated above show, the cost of repairing/replacing a broken undertray will depend heavily on the level of damage, what type of car it's on, and also where you are in the country.

What is a car undertray and what does it do?

A car's undertray helps to protect the bottom of the engine and the ancillary components, such as the alternator and air conditioning pump, from road dirt and water.

Another key function of undertrays on certain cars is to improve cooling, as they help to keep a low-pressure zone in the engine compartment, improving flow through the engine's radiator.

In most cases, it is a thin, shaped panel made of plastic that attaches to the wheel arch liners on each side and the bumper at the front. On many cars, they need to be removed to work on the engine and do servicing.

How do undertrays get damaged?

There are many ways an undertray can get damaged. Common ways include when driving over very rough terrain, entering very steep car parks, or even hitting large puddles or other hazards on the road.

One of the common gripes from mechanics is that undertrays are often fitted with plastic pop-in fasteners as well as proper screws or bolts. These clips are easy to break when removing, and if left, can easily cause the undertray to hang lower than it should, making it even more susceptible to damage.

Does my car need an undertray?

It's highly advisable to replace a broken undertray to prolong the life of your car and reduce future bills. In general, car manufacturers don’t fit things that aren’t needed, and the undertray serves an important purpose of protecting your engine and related components.

Whilst not having an undertray is unlikely to cause any immediate problems, it will vastly increase the amount of water, stones and road dirt that can get to vital parts of your engine, such as the auxiliary belt, alternator, power steering pump and radiators.

None of these parts work well when subject to water and dirt, and as such, driving for a prolonged time – especially through winter – without an undertray could easily reduce their lifespan.

Why is replacing an undertray so expensive?

In some cases, replacing an undertray also requires other new parts, such as wheel arch liners or supporting bracketry; these can all raise the price of the repair.

One factor that will massively affect the price is whether the replacement part is a genuine one or not - manufacturers differ in parts pricing, and certain luxury brands are known to be very costly.

If this is the case, it might be possible for your mechanic to find and fit a secondhand undertray, bought from a used spares or breakers yard - though this can come with its own challenges.

Author - Joseph Law

Joseph has been writing about cars for over eight years and writing for Bumper for over three, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.