Catalytic Converter Efficiency Codes – Cause and Repair – The Trainer Video Series

Catalytic Converter Efficiency Codes – Cause and Repair – The Trainer Video Series

Motor Age — The catalytic converter is a simple device really. No moving parts, no periodic adjustments needed. And it serves a vitally important purpose; that is, to make sure that what leaves the tailpipe is as clean as it can be. There is one weakness to the design, though. The exhaust gasses going in to the cat have to be maintained in a very narrow lambda range. Feed gasses that are too lean (excess) or too rich (excess fuel) will both cause the cat’s temperature to rise outside of the limits it can handle and can cause permanent damage to the chemical substrate contained within.

And that just won’t do.

The Engine Control Module (ECM) is responsible for just one thing – to make sure that the feed gasses getting to the catalytic converter remain within those narrow boundaries. If things get out of control, Diagnostic Trouble Codes are set to alert the professional service technician that his (or her) help is required to protect the cat. Ignoring these warnings can lead to the meltdown or damage of the substrate, excessive emissions out of the tailpipe, and the dreaded P0420/P0430 “Catalyst Efficiency Below Threshold” trouble code(s).

Often, when these codes set, the only cure is a replacement converter. However, failure to determine the root cause of the converter’ demise will almost certainly lead to the same fate for that replacement. While cats can die of old age or by impact that causes the substrate to separate from the housing and break into little pieces, those failures tend to be the exception rather than the rule. In many cases, the converter itself is perfectly fine with a long life ahead of it and the ECM simply made a mistake in its testing. In many others, failure to address existing drivability issues results in the cat’s demise. And in yet others, it is our own improper service techniques that result in converter failure.

With the help of Tenneco’s Joe Bacarella, we’ll cover all that and more in this month’s edition of “The Trainer”.

Source: Motor Age

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.