Question 1

What is the EGR valve and what does it do?

Accepted Answer

The EGR valve (Exhaust Gas Recirculation) recirculates part of the exhaust gases back to the intake to reduce combustion temperature and decrease nitrogen oxide (NOx) emissions. It is a mandatory component in modern diesel and petrol engines to comply with Euro 5 and Euro 6 regulations.

Question 2

How do I know if my EGR valve is faulty?

Accepted Answer

The most common symptoms are: loss of power, irregular idle, black exhaust smoke, increased consumption, jerking when accelerating and check engine light on. The valve usually gets clogged with carbon deposits, especially in diesel engines with short journeys.

Question 3

Can the EGR valve be cleaned or does it need replacing?

Accepted Answer

It depends on the condition. If it's just dirty with carbon deposits, it can be cleaned by removing it and using special products. If the mechanism is damaged, permanently stuck or has leaks, it needs to be replaced. Replacement EGR valves include gaskets and guarantee optimal operation.

Question 4

Why does the EGR valve get clogged?

Accepted Answer

It gets clogged by accumulation of carbon deposits and soot from combustion. Factors that accelerate clogging are: short journeys without warming up the engine, low engine speed, poor quality oil, dirty air filter and poor combustion. Proper maintenance prevents clogging.

Question 5

Is it legal to disable the EGR valve?

Accepted Answer

No. Disabling or disconnecting the EGR valve is illegal in the UK and Europe. The vehicle will fail the MOT test for high NOx emissions, may damage the engine and the fine can reach £1,000. Additionally, it increases pollution and can affect the turbocharger and particulate filter.