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mattmag
Premium,ExMod 2000-03
join:2000-04-09
NW Illinois
kudos:3

1 edit

1 recommendation

reply to Anonymous_

Re: catalytic converter? P0240

said by Anonymous_:

I was behind a bus that was pouring out a lot of smoke, when the CEL came on.

You were behind a smoking bus *twice* to make it come on? You said you already had the code cleared once. And, that's a virtually impossible scenario to cause that code anyway.

What sensor do you plan on replacing on a blind guess? Upstream or downstream? I really don't understand why people want to come up with every reason under the sun why this code sets. There is a converter failure code so you want to replace the oxygen sensor. If a code sets for an cylinder #4 misfire, are you going to replace a headlamp?

I'm being straight here--- BOTH related-bank oxygen sensors MUST BE operating properly for this failure code to occur. The computer is measuring exhaust oxygen content BOTH before AND after the catalyst to determine its efficiency. A malfunctioning O2 sensor strictly prevents this diagnostic cycle from running, and will set a SENSOR failure code, NOT a catalyst code. There are no "false positives" here.

I will add that the best course of repair is proper diagnosis. Get the system tested, preferably by a shop that can scope the components to get the correct picture. Like I said, very high percentage its the converter. Oxygen sensor failure is very rare.


Anonymous_
Anonymous
Premium
join:2004-06-21
127.0.0.1
kudos:2
Reviews:
·Time Warner Cable
said by mattmag:

said by Anonymous_:

I was behind a bus that was pouring out a lot of smoke, when the CEL came on.

You were behind a smoking bus *twice* to make it come on? You said you already had the code cleared once. And, that's a virtually impossible scenario to cause that code anyway.

What sensor do you plan on replacing on a blind guess? Upstream or downstream? I really don't understand why people want to come up with every reason under the sun why this code sets. There is a converter failure code so you want to replace the oxygen sensor. If a code sets for an cylinder #4 misfire, are you going to replace a headlamp?

I'm being straight here--- BOTH related-bank oxygen sensors MUST BE operating properly for this failure code to occur. The computer is measuring exhaust oxygen content BOTH before AND after the catalyst to determine its efficiency. A malfunctioning O2 sensor strictly prevents this diagnostic cycle from running, and will set a SENSOR failure code, NOT a catalyst code. There are no "false positives" here.

I will add that the best course of repair is proper diagnosis. Get the system tested, preferably by a shop that can scope the components to get the correct picture. Like I said, very high percentage its the converter. Oxygen sensor failure is very rare.

I'll just wait tell I need to do the smog test (you bet I going to clear the code before I get the test done)

if it passes then it's a faulty SENSOR. if it fails I get it fixed
--
Well, does your car at least turn into something else? Sometimes I turn it into a trashcan. Hmm...