Pattern Flaws: EGR Valve

This report introduces a series of articles that addresses common "pattern failures"—basically design flaws that affect a large number of vehicles. The term literally means failure along a pattern, that is, similar and repeatable failures both in time and nature.

Wear and Tear
Many of the typical auto parts problems are of a design-specific nature. That is, certain parts designs tend to fail along a pattern irrespective of vehicle make and model. For instance, all air filters regardless of vehicle make and model will eventually get clogged with dirt and need replacement at more or less specific intervals. All vulcanized rubber engine mounts will eventually compress to the point of failure, due to the constant forces being exerted on them—again, at more or less an approximate time.


In this series, though, we'll show parts pattern failures encountered at my auto repair business, which seem to follow along specific make and model lines. Note that this approach is solely for your own information, and is not intended as some form of criticism on any particular auto manufacturer, but as a tool to help you diagnose and repair the problem if it exists on your own vehicle.


That said, let's start with the pattern failure of an EGR conduit pipe on a Ford Focus. The pipe is used to conduct hot exhaust gas from the manifold to the EGR valve. Not every manufacturer uses this type of external pipe; and some engine designs don't really necessitate their use with the type of EGR systems installed on them.


I haven't seen EGR pipe pattern failures of this nature for many years and miles of operation on assorted makes and models, though. The failure involves separation of the pipe and mounting flange at the exhaust manifold. This results in an exhaust leak that will initially be only intermittently audible to the driver, but will eventually become progressively louder. Not only will engine performance be noticeably impaired, but the "Service Engine Soon" MIL will illuminate as well. Besides that, exhaust will likely enter the vehicle's cabin, a condition dangerous to occupants who may be unaware of its presence.