An exhaust that has suddenly become loud, started rattling or is hanging lower than it should is hard to ignore, and an emissions warning light isn't much easier. NRH Autoworks repairs exhaust systems and traces emissions faults at our garage on Windsor Road in Bray, for drivers from Maidenhead and the surrounding area.
Enter your registration on the enquiry form and describe what you're hearing or seeing, any warning lights, and where on the car a noise seems to be coming from. If part of the exhaust is visibly damaged or hanging down, a photo helps. We'll get back to you by phone or email to arrange a look.
What we can help with
- Exhaust inspections and leak repairs
- Silencers, pipes and flexi sections
- Mountings, hangers and clamps
- Catalytic converter replacement
- Lambda sensor, EGR valve and NOx sensor faults
- DPF regeneration
Signs of an exhaust or emissions problem
- The car is noticeably louder than it used to be
- A blowing, chuffing or roaring sound when accelerating
- Rattling or metallic vibration from underneath
- Part of the exhaust hanging low or knocking on the body
- Exhaust fumes you can smell inside the car
- An engine management light alongside a loss of power
- A DPF warning light on a diesel used mainly for short journeys
What goes wrong with exhausts
Exhausts live a hard life underneath the car, exposed to heat, water and road salt, and corrosion is the usual cause of failure. Silencers rust through, joints start to blow, and the rubber hangers and brackets that support the system perish or snap, leaving it to rattle against the body. Short journeys make matters worse, because condensation sits inside the system instead of being driven off by heat.
An exhaust is made up of several sections, so a fault doesn't necessarily mean replacing the whole thing. Often it's one silencer, one length of pipe, a failed mounting or the flexi section near the engine, which is woven to absorb engine movement and eventually frays and leaks. Catalytic converters fail as well, either by breaking up internally and rattling or by becoming blocked. We'll inspect the system from front to back and tell you which parts need attention.
Why a leaking exhaust shouldn't be left
A blowing exhaust is more than a nuisance. Leaks ahead of the silencers can allow fumes into the cabin, and exhaust gas contains carbon monoxide, which you can't see or smell. A leak can also upset the sensors that manage the engine, bringing on a warning light, and excessive noise or a leaking system can cause an MOT failure. If you can smell fumes inside the car, drive with the windows open and have it checked promptly.
Emissions faults and sensors
Modern engines rely on sensors in the exhaust to keep emissions in check. Oxygen sensors, also called lambda sensors, measure how completely the fuel is burning so the engine can adjust its mixture. The EGR valve feeds a little exhaust gas back into the engine to reduce emissions, and it clogs with soot and sticks. Many newer diesels have NOx sensors as well. A fault in any of them brings on the engine management light, but the part named by the code isn't always the culprit, so we test first.
Diesel particulate filters (DPF)
A DPF traps soot from a diesel's exhaust and burns it off during longer, hotter runs. When a car does mostly short journeys that never happens, the filter loads up, and you get a warning light and eventually limp mode. We carry out forced DPF regeneration using diagnostic equipment, which makes the car run a controlled burn-off in the workshop. First, though, we establish why it blocked, because sensor faults and EGR problems cause it as often as driving habits do.
To be straightforward: we don't offer DPF cleaning, meaning the off-car or chemical cleaning services some specialists provide. If a filter is too heavily blocked or damaged to regenerate, we'll tell you and advise on the options. What we won't do is remove one. Taking the DPF off a car that's used on the road is illegal and an MOT failure.
Exhausts & Emissions: common questions
Do you do DPF regeneration in Maidenhead?
Yes. If your diesel's DPF warning light is on, or the car has gone into limp mode because the filter is blocked, we can run a forced regeneration at our garage in Bray, near Maidenhead, and check why the filter didn't regenerate by itself. We don't offer DPF cleaning or removal. If the filter is beyond regeneration we'll tell you and talk through the options.
Does a noisy exhaust mean I need a whole new system?
Not usually. Exhausts are built in sections, and in most cases only the failed part (a silencer, a pipe, a flexible joint or a mounting) needs replacing. We'll inspect the full system and explain which sections are affected, so you aren't paying to replace parts that are still in good condition.
What's causing the rattle under my car?
Common causes are a broken exhaust hanger letting the system knock against the body, a loose heat shield, or internal baffles that have come adrift inside a silencer. The catalytic converter can also rattle if its internal core has broken up. We'll identify the source when the car is on the ramp.
Can you clear a blocked DPF?
Often, yes. We can carry out a forced regeneration using diagnostic equipment, provided the filter isn't too heavily blocked and we've dealt with whatever caused it. We don't offer DPF cleaning, so if regeneration isn't possible we'll explain that and advise on your options. Tell us which lights are on and how the car is used.
Why does my DPF keep blocking?
Usually because the car rarely gets hot enough for long enough to burn the soot off, which is typical of short local journeys. Faulty pressure or temperature sensors, a sticking EGR valve, injector problems and the wrong engine oil can all contribute. Repeated blocking needs the cause found, not just another regeneration.
How do I get a quote for an exhaust repair?
Send an enquiry with your registration so we can identify the exact system fitted to your car, and describe the noise or damage. A photo helps if something is visibly broken. We'll contact you by phone or email; in most cases we'll need to inspect the exhaust before confirming what's required.