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Recently I had the engine heater warning lamp (coil symbol) turned on while driving on my 2009 VW Polo diesel. The engine started losing power when going at a speed of over 100 km/h.

After a couple of days, the lamp turned off.

My mechanic told me that the EGR valve is going bad and that it needs to be changed. After the change (an expensive one, at least for me) there were no more issues.

However, I've later been told by some friends that the changing of the valve was not necessary. Is there any truth to that?

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    Welcome to Motor Vehicle Maintenance & Repair! Jan 13 at 12:50
  • Thank you very much.
    – Mate Mrše
    Jan 13 at 12:53
  • Unsure: the symptom from my previous 2008 Skoda diesel (with VW engine) was no warning, just a lack of power due to the turbo being disabled by the EMS, which would happen whenever a significant amount of power was used, such as hard acceleration, high speed or a steep hill. The turbo would be re-enabled when the engine was restarted. There are ways of cleaning the EGR valve, such as removing and physically cleaning, or by solvent applied through the air system. Jan 13 at 13:10
  • I had similar issues about 5 years ago with the egr valve on my car. Cleared the codes and then fitted a stainless steel blanking plate with an 8mm hole - no more issues from the valve at all. Just enough exhaust gas comes through to fool the ecu... EGR valve is 150 or more and the blanking plate 5...
    – Solar Mike
    Jan 13 at 14:01
  • I have heard of people fitting a cheap 'pattern' valve only for it to fail after a few weeks. Jan 13 at 14:03
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The glow light flashing and a reduction in power is a classic symptom of an EGR valve problem on VW group diesel engines, so it sounds likely that the mechanic made the right call on replacing it, especially as your car is working again. If your friends are saying it wasn't an EGR valve they are probably wrong.

If your friends are saying that the valve could have been repaired instead of replaced then they could be right. Sometimes EGR valves get clogged up with soot and can be cleaned instead of replaced, however it may not be the best option for you. The biggest cost with the replacement is the labor, and the difference in cost between replacing the part and repairing it isn't that much. A new part is much more likely to work flawlessly, a mechanic could repair the valve and test it only to find once it's back on the car there was an undetected issue. It's better to put on a guaranteed part than one that could still be faulty.

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Nobody here can tell if your EGR value is irreparable damaged or not. Some valve models are frail and easily damaged, others are quite robust and cleanable until the damage is too big.

Most of the time the failure is that the valve is full of carbon and the actuator cannot move the vale. Some models are quite robust and just seize, but have a good probability that they work again after a thorough cleaning. Other models fail irreparable early.

Diesel cars that see no regular long drive on high load are especially prone to blocked EGR valves. The problem gets worse on prolonged oil changing cycles.

Now the average mechanic has a hard time explaining to you that he must periodically remove a certain item (perhaps on an hard to reach place), clean it, reinstall it and hope that the actuator is still fine.

It is much easier to say "expensive-thingy-broken-must-replace", especially if the cost of replacement (100% success rate) is comparable or less to the cost of labor with the risk of non-success involved.

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  • Moral of the story, change your damn oil on time. Especially in diesels, those things shoot soot into the oil or something.
    – lericson
    Jan 15 at 14:48

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