# Auto Dopers--Urgent Car Repair Question **URL:** \ **Category:** Factual Questions\ **Created:** [September 2, 2008, 2:53pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677 "2008-09-02T14:53:44Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [September 3, 2008, 2:26pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/21 "2008-09-03T14:26:19Z")
> [@Bad\_Samaritan](#): > > Ok, but wouldn’t a “stopped up cat” possibly exhibit other symptoms, such as engine hesitation, poor performance, or stalling? The OP only mentioned “check engine light” which could be a number of things. How bout a glowing cat? I had one get clogged and the car ran like shit then I smelled _hot_ and looked under the car and saw the thing glowing. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [September 3, 2008, 3:55pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/22 "2008-09-03T15:55:29Z")
> [@Rick](#): > > Before we go buy a new converter I have a few questions. > First off what lead the shop to determine that the converter was “stopped up” To the best of my knowledge there is no fault code for a plugged converter. It is not unreasonable to expect fuel trim codes or miss fire codes as a result of a plugged converter, but the mere presence of these codes does not automatically condemn the converter. > Secondly Cats don’t go bad and get plugged on their own when everything else on the car is running with in specifications. Something failed that caused the converter to get plugged. Replacing the converter without repairing the underlying cause is frankly pissing away money. The failure will only reoccur. > I agree with **Gary T** that a quality of converters can vary greatly, and cheap ones are not necessary worth the effort. I have seen posts on professional repair forums where a car failed a smog test, and the cat was condemned. An aftermarket converter was installed, and emissions went up by more than 50% :smack: Your data on fault codes for converters is out-of-date. Post-1996 cars do have cat fault codes. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 3, 2008, 10:06pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/23 "2008-09-03T22:06:26Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > Your data on fault codes for converters is out-of-date. Post-1996 cars do have cat fault codes. Go back and read what I wrote. I said there are no fault codes for a “stopped up” converter. ::: Wanders over to All Data for Windows::: Yup, there are several codes that might indicate a damaged cat P0420 Catalyst efficiency below threshold P1148 Closed loop malfunction P0301-0306 Miss fire. You will note that none of these flat out say the converter is plugged (“stopped”) up. The system has no way to tell the converter is plugged. So unless in Tenn stopped up, is an all purpose term that means does not work correctly, I stand by my answer. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [September 4, 2008, 1:06pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/24 "2008-09-04T13:06:31Z")
> [@Rick](#): > > The system has no way to tell the converter is plugged. So unless in Tenn stopped up, is an all purpose term that means does not work correctly, I stand by my answer. I agree, unless there are two pressure sensors on the cat the computer won’t know if the cat is plugged or if there’s a banana in the tailpipe. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 4, 2008, 1:42pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/25 "2008-09-04T13:42:12Z")
> [@Uncommon\_Sense](#): > > I agree, unless there are two pressure sensors on the cat the computer won’t know if the cat is plugged or if there’s a banana in the tailpipe. There are no fault codes listed for Ford products that would indicate such. I have never seen exhaust system pressure sensors on any car. ---
**Author:** ![danceswithcats](https://avatars.discourse-cdn.com/v4/letter/d/9e8a1a/32.png) [@danceswithcats](https://boards.straightdope.com/u/danceswithcats)\ **Post date:** [September 4, 2008, 7:56pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/26 "2008-09-04T19:56:57Z")
> [@Rick](#): > > There are no fault codes listed for Ford products that would indicate such. I have never seen exhaust system pressure sensors on any car. Yeah, but is there a banana in the tailpipe code? Something like P $1.99/lb in your car’s arse :eek: ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [September 4, 2008, 8:28pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/27 "2008-09-04T20:28:39Z")
> [@Uncommon\_Sense](#): > > I agree, unless there are two pressure sensors on the cat the computer won’t know if the cat is plugged or if there’s a banana in the tailpipe. The oxygen sensors, perhaps? ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [September 4, 2008, 9:13pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/28 "2008-09-04T21:13:27Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > The oxygen sensors, perhaps? Their readings can indicate that the catalyst’s job is not getting done, but not why it’s not getting done. They do not detect pressure. ---
**Author:** ![NurseCarmen](https://avatars.discourse-cdn.com/v4/letter/n/5daacb/32.png) [@NurseCarmen](https://boards.straightdope.com/u/NurseCarmen)\ **Post date:** [September 4, 2008, 10:19pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/29 "2008-09-04T22:19:25Z")
> [@danceswithcats](#): > > Yeah, but is there a banana in the tailpipe code? > > Something like P $1.99/lb in your car’s arse > > :eek: Well, since the potassium in bananas is rumored to stop eye twitches, I suspect the code would be a blinker suddenly stops working. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 5, 2008, 1:55am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/30 "2008-09-05T01:55:41Z")
> [@nursecarmen](#): > > well, since the potassium in bananas is rumored to stop eye twitches, i suspect the code would be a blinker suddenly stops working. :d ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 5, 2008, 2:03am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/31 "2008-09-05T02:03:47Z")
> [@Rick](#): > > :d What no smilies? ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [September 5, 2008, 2:47am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/32 "2008-09-05T02:47:09Z")
> [@Rick](#): > > What no smilies? 😛 ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 5, 2008, 3:08am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/33 "2008-09-05T03:08:14Z")
> [@Fear\_Itself](#): > > 😛 ::: Shakes fist::: ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [September 5, 2008, 4:34am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/34 "2008-09-05T04:34:57Z")
> [@Rick](#): > > ::: Shakes fist::: I am sorry, \*that \*smilie is not enabled in vBulletin 3.7.3 ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [September 5, 2008, 11:37am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/35 "2008-09-05T11:37:35Z")
> [@Gary\_T](#): > > Their readings can indicate that the catalyst’s job is not getting done, but not why it’s not getting done. They do not detect pressure. Nobody said they needed to. The problem was in that area, the mechanic dismantles it—BINGO! We have a blocked-up cat. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [September 5, 2008, 12:25pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/36 "2008-09-05T12:25:15Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > Nobody said they needed to. > > The problem was in that area, the mechanic dismantles it—BINGO! We have a blocked-up cat. Great, so what was the underlying cause of the converter failure? As I said before these things don’t roll over and die all by themselves. ---
**Author:** ![Uncommon\_Sense](https://avatars.discourse-cdn.com/v4/letter/u/f9ae1b/32.png) [@Uncommon\_Sense](https://boards.straightdope.com/u/Uncommon_Sense)\ **Post date:** [September 5, 2008, 12:43pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/37 "2008-09-05T12:43:44Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > Nobody said they needed to. > > The problem was in that area, the mechanic dismantles it—BINGO! We have a blocked-up cat. Sure, but that means taking apart the exhaust to find the problem. You made it sound like it could be diagnosed from the computer. A code (or codes) along with the performance of the vehicle and a visual inspection of the cat _might_ lead the mechanic to suspect the cat is blocked up. There just isn’t a foolproof way to say for certain that that’s the case or why it happened. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [September 5, 2008, 4:28pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/38 "2008-09-05T16:28:20Z")
> [@Uncommon\_Sense](#): > > How bout a glowing cat? I had one get clogged and the car ran like shit then I smelled _hot_ and looked under the car and saw the thing glowing. I’ve had 2 cats plug up and they glowed red. ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [September 6, 2008, 10:50am UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/39 "2008-09-06T10:50:35Z")
All fixed. Car runs good. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [September 6, 2008, 1:34pm UTC](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677/40 "2008-09-06T13:34:47Z")
> [@Bosda\_Di\_Chi\_of\_Tricor](#): > > All fixed. > > Car runs good. You never said whether it ran badly before though. [Previous page](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677.md?page=1) [Next page](https://boards.straightdope.com/t/auto-dopers-urgent-car-repair-question/461677.md?page=3)