Exhaust Repairs and Emissions in Devon

Your exhaust carries burnt gases away from the engine, quietens the noise and cleans up what comes out of the tailpipe. When something goes wrong you may hear it first, or the dashboard may tell you, or the car may fail the emissions part of its MOT.

Automaster is an independent garage at Longcombe Cross, near Totnes, and we look after drivers across South Devon. Below we explain exhaust repairs and replacement, catalytic converters, diesel particulate filter (DPF) problems and emissions diagnostics in plain English, with the details to give us when you ask for a quote.

Why is my exhaust loud, rattling or blowing?

A loud exhaust usually means a hole or a blown joint, caused by rust, a failed gasket or a broken mounting. Other signs are a rattle from underneath, a deeper roar when you accelerate, a hissing or ticking from the manifold area, or a dangling pipe.

Exhausts can sometimes be repaired in sections, and sometimes a complete or part replacement is the sensible route, especially where rust has spread. Which applies depends on the vehicle and how far the damage goes. A damaged exhaust can fail an MOT and in some cases can drop off, so it is wise not to leave it. Tell us the make, model and year and where the noise seems to come from.

What does a catalytic converter do, and how do I know it has failed?

The catalytic converter sits in the exhaust and changes harmful gases into less harmful ones. When it fails, you may see an engine warning light, poor performance, a smell like rotten eggs, a rattle from inside the unit, or an emissions failure at the MOT.

A converter often fails because of another fault, such as an engine misfire, oil burning or a faulty sensor, so replacing it without finding the cause can mean the new one fails too. That is why we diagnose first. Tell us about any warning light, any recent engine problems and whether the car feels down on power, and we can inspect and quote.

What is a DPF and why does my warning light keep coming on?

A diesel particulate filter traps soot from a diesel engine. To keep it clear, the car burns the soot off in a process called regeneration, which needs a long enough run at sustained speed. Lots of short journeys can stop that happening, and the filter slowly blocks.

A DPF warning light is the car telling you that it needs attention. If you ignore it, the car may go into limp mode with reduced power, and a badly blocked filter can be expensive to put right, so act early. Depending on the cause, we may be able to clean the filter or repair the related fault, such as a sensor, a pressure pipe or an EGR problem. A replacement may be needed in some cases, and only an inspection will tell.

• Warning light on the dashboard
• Reduced power or limp mode
• Mostly short journeys
• Smell of fuel or higher fuel use

How are emissions problems diagnosed?

Emissions faults are linked to the whole engine, not just the exhaust. Oxygen sensors, the air flow sensor, the fuel system, ignition and exhaust gas recirculation can all push emissions out of limits. A diagnostic scan reads stored fault codes and live data, which shows us which system to test.

A code points to a circuit or system, not automatically to a part, so we test before replacing anything. If your car has failed the emissions part of its MOT, bring us the failure sheet or tell us the reason given. Please also tell us about any smoke from the exhaust, rough running or warning lights, and whether it uses petrol or diesel.