05 s40 intermittent check engine light.

marcusnea · Post by **marcusnea** » 11 Dec 2012, 16:13

I have a intermittent check engine light that is giving me a catalytic converter code of catalyst efficiency below threshold, I get no rotten egg smell the light is intermittent. the car has 228k, can the converter just be worn out? any help please!

Post by **zulu-v40** » 12 Dec 2012, 05:17

Before replacing the catalytic converter, you might explore replacing your oxygen sensors. On my car, there are two that connect directly to the converter, one on top and one on bottom. You can do a google search to find out how to test them with a voltmeter.

With that said, the catalytic converter doesn't have to smell terrible for it to be malfunctioning. Put the car up on ramps. Get underneath and tap on the catalytic converter. Does it sound like there are bits and pieces moving around inside? If so, consider replacing your catalytic converter. I replaced mine with an aftermarket converter that is working very well. You don't have to break the bank to replace it with an OEM part.

Before replacing it, I did remove and carefully inspect it. The honeycomb inside was dented and restricting air flow. I tried bathing it in a degreasing solution overnight and sprayed out the debris, which eliminated the code temporarily, but it did return shortly thereafter.

AndyB2005S40 · Post by **AndyB2005S40** » 04 Jul 2013, 19:53

I had a similar problem some years back, around 102K miles....Duh! Turned out I didn't fully plug in the upper OXS...Plugged it in, heard the "click" and I was off and running, never looked back...Big congrats on having (by now, well over) 228K on an '05 S40....I hit 153K the other week, and am hoping for at least 250K before it dies or becomes a real money pit....I'm sure you've got great war stories, surprise emergency (red) warnings about the electrical system, etc.