# Catalytic Converter Questions **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** toyota, repair\ **Created:** [December 17, 2008, 1:13pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521 "2008-12-17T13:13:56Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![ForeverFam](https://avatars.discourse-cdn.com/v4/letter/f/7ea924/32.png) [@ForeverFam](https://community.cartalk.com/u/ForeverFam)\ **Post date:** [December 17, 2008, 1:13pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/1 "2008-12-17T13:13:56Z")
I have a 01 Toyota Corolla with apprx 90k. The check engine light went off & we took it to the shop. They told us that the catalytic converter needs to be replaced & it would cost $1400 but we could wait until we needed to pass state inpsection (which is Aug '09). My question has two parts. 1. What makes a catalytic converter go bad (was there something we didn’t do in regards to maintenance)? 2. Can we really wait on this or does that hurt the engine? ---
**Author:** ![common-sense-answer](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/common-sense-answer/32/716_2.png) [@common-sense-answer](https://community.cartalk.com/u/common-sense-answer)\ **Post date:** [December 17, 2008, 1:30pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/2 "2008-12-17T13:30:02Z")
You Ask 2 Very Good Questions I will ask a few. Is this a Toyota Dealer you went to or an independent? Do you know the specific code(s) that set the “engine light”? (May be on your receipt) Is the light now staying turned “off”? I live where there is no State Inspection. Can your car pass like this? Why are you waiting? Is it to put off the expense? I understand. You can be doing damage to things that otherwise may be OK, by continuing to drive it. We may be able to advise you. This gets tricky. This site gets a lot of catalytic convertor issues, partly because many engine problems can impact the convertor. I believe these are easy to misdiagnose. There is a good chance that something is causing this problem besides the convertor or instead of the convertor. Did they venture a guess as to why they thought it went “bad”? Post the code(s) here. If you don’t know them and the light comes on or is on, get the code(s) read at a big chain retail Auto Parts store. Call them first, Many offer this service for free. Write them down exactly like PO455, etcetera. Can you give us more info? ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [December 17, 2008, 2:29pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/3 "2008-12-17T14:29:44Z")
Go to an independent shop for a much cheaper fix. An after-market catalytic converter is fine…IF it’s needed. It’s too easy (and, profitable) for mechanics to just change parts. The check engine light code never says that a parts needs to be changed. Never. The code says that there is something different in the signal from a sensor (or, actuator). Checks, and tests, will aid in determining what the cause of the problem is. Here is a checklist of what the mechanic should check for when the catalytic converter code is set. (You can copy this stuff and give to your mechanic. Even a good, conscientious, mechanic can forget some checks.) [http://www.obd-codes.com/p0420](http://www.obd-codes.com/p0420) ---
**Author:** ![donnadodsonartist](https://avatars.discourse-cdn.com/v4/letter/d/3da27b/32.png) [@donnadodsonartist](https://community.cartalk.com/u/donnadodsonartist)\ **Post date:** [December 17, 2008, 2:41pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/4 "2008-12-17T14:41:52Z")
that happened to my 01 toyota tacoma and it was replaced under 7yr/100k mile toyota warranty- do you know the warranty for your car’s emission system? if the check engine light is on, it’s usually a good idea to deal with it in a timely manner because sometimes the light masks a hidden problem with the car that will take more parts and more diganostics to find and fix. if it starts blinking, that is worse. ---
**Author:** ![Whitey](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/whitey/32/24680_2.png) [@Whitey](https://community.cartalk.com/u/Whitey)\ **Post date:** [December 17, 2008, 4:53pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/5 "2008-12-17T16:53:47Z")
Shop around. You might find a better price. However, don’t go too cheap. An aftermarket or rebuilt catalytic converter might not solve the issue to the satisfaction of you and your emissions inspector. Based on the price you were quoted, your catalytic converter is probably the same piece as your exhaust manifold. That is why this probably isn’t the cheap $79 catalytic converter you might have bought for previous cars. If you opt for a lower price quote, make sure you get a guarantee in writing that it will pass emissions standards in your state. Otherwise, you might find you have made a decision that is penny wise and pound foolish. ---
**Author:** ![ForeverFam](https://avatars.discourse-cdn.com/v4/letter/f/7ea924/32.png) [@ForeverFam](https://community.cartalk.com/u/ForeverFam)\ **Post date:** [December 17, 2008, 11:14pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/6 "2008-12-17T23:14:11Z")
Thank you for all your responses. We went to a reputable independent shop that speficially works on Honda & Toyota vehicles. We did not ask about the codes that showed up. Our mechanic said he just reset it but it may come back on after approx 60 miles of driving. He made it sound like it would be no big deal to let the car run as is but I’m somewhat skeptical.Something in my mind must cause a $1400 repair. We just got the car looked at yesterday. We have the money to make the repair but my husband felt if the mechanic said it was okay then we shouldn’t worry. When check engine light comes back on, I may take it to a local dealer just to see what they say. ---
**Author:** ![BarryNNJ](https://avatars.discourse-cdn.com/v4/letter/b/bbe5ce/32.png) [@BarryNNJ](https://community.cartalk.com/u/BarryNNJ)\ **Post date:** [December 17, 2008, 11:40pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/7 "2008-12-17T23:40:42Z")
Your catalytic converter was covered for 8 years or 80,000 miles, whichever came first, so it seems like you just missed the cutoff for a warranty repair. If you’re going to try to plead a case with Honda, you should do it now, before you add miles and years. Be prepared to hear “sorry,” but you might try anyway. ---
**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\ **Post date:** [December 17, 2008, 11:42pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/8 "2008-12-17T23:42:29Z")
We can’t really answer that question unless we know more, most important any errorr codes. Those codes may have been deleted. If it comes back, get the actural codes and let us know what they are, then we can offer a more informed opinion. Yes it is possible that there could be something wrong, but it may not harm anything on your car, it is also possible it could cause additional harm. The code should be something like “P0123” ---
**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\ **Post date:** [December 17, 2008, 11:57pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/9 "2008-12-17T23:57:06Z")
Ummm, the OP has a Toyota. ---
**Author:** ![ForeverFam](https://avatars.discourse-cdn.com/v4/letter/f/7ea924/32.png) [@ForeverFam](https://community.cartalk.com/u/ForeverFam)\ **Post date:** [December 18, 2008, 12:56am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/10 "2008-12-18T00:56:34Z")
My husband double checked the reciept it reads the code was PO420 ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [December 18, 2008, 1:25am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/11 "2008-12-18T01:25:21Z")
Instead of us, out here in cyberspace, going around the same mulberry bush, why don’t you read the existing responses, and click the links. I don’t feel that, unless you report some changes, there is anything fruitful to add. Good luck. ---
**Author:** ![common-sense-answer](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/common-sense-answer/32/716_2.png) [@common-sense-answer](https://community.cartalk.com/u/common-sense-answer)\ **Post date:** [December 18, 2008, 1:41am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/12 "2008-12-18T01:41:30Z")
This Is The Link For Code PO420 That Hello Kit Has Already Provided He anticipated the code. Do reread his original posting, as he is advising you. There are a lot of possible reasons for code PO420, other than a bad catalytic convertor. Link: > **[P0420 Catalyst System Efficiency Below Threshold](https://www.obd-codes.com/p0420)** > > How to diagnose, repair, and info on symptoms and causes of a P0420 engine code which means the catalytic converter is no longer performing at a normal level. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [December 18, 2008, 3:05am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/13 "2008-12-18T03:05:19Z")
I would wait. My daughter has this same code on her 03 Corolla. The last thing I will replace will be the converter. There are many posts on this site about this code and I haven’t seen one where the cat solved the problem, in fact some never reported back that the problem ever got solved but many were not solved by the usual parts. ---
**Author:** ![oldschool](https://avatars.discourse-cdn.com/v4/letter/o/e19adc/32.png) [@oldschool](https://community.cartalk.com/u/oldschool)\ **Post date:** [December 18, 2008, 3:31am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/14 "2008-12-18T03:31:40Z")
I really wish we could get a handle on why so many cat failures.My WAG is a misdiagnosis. The main reason I have replaced cats was for rattling the BMW E-39(5series)was bad for this.We also get a lot of posts from people that went ahead and got the cat and are still dealing with that “low efficiency” error code,perplexing. ---
**Author:** ![pleasedodgevan](https://avatars.discourse-cdn.com/v4/letter/p/51bf81/32.png) [@pleasedodgevan](https://community.cartalk.com/u/pleasedodgevan)\ **Post date:** [December 18, 2008, 4:30am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/15 "2008-12-18T04:30:12Z")
The engine won’t be hurt but the downstream sensor could be. If you care about environmental things, there could be up to eight times more hydrocarbon emissions pushed out the exhaust until the Aug inspection. I don’t believe that the converter should cost that much. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [December 18, 2008, 5:09am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/16 "2008-12-18T05:09:15Z")
If your car has no drivability problems, don’t worry about it until you MUST. if your exhaust system is gas-tight (plug the tailpipe and check for leaks) you could first replace the oxygen sensors (both) as it is the reading from these sensors that is making the light come on. Half the time it’s just a bad connection. Perhaps the CEL will never come back on…And you are in a rush to pay someone $1400?? PT Barnum was right… ---
**Author:** ![Manolito](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/manolito/32/3070_2.png) [@Manolito](https://community.cartalk.com/u/Manolito)\ **Post date:** [December 18, 2008, 7:22am UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/17 "2008-12-18T07:22:19Z")
90k miles, OBD 2 computer, code for catalytic converter. If it were mine, since I don’t have the tools to diagnose an oxygen sensor properly, I would spend my money on a new front oxygen sensor(s) before spending a penny at a shop. The sensors are getting long in the tooth anyway for OBD 2, which is quite particular about having perfectly-functioning O2 sensors, so if it turns out to be something else, it was not a complete waste of money to replace the sensor(s). Check your owners manual. If you are close to the recommended replacement interval for the oxygen sensors, I would start there. ---
**Author:** ![Whitey](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/whitey/32/24680_2.png) [@Whitey](https://community.cartalk.com/u/Whitey)\ **Post date:** [December 18, 2008, 2:28pm UTC](https://community.cartalk.com/t/catalytic-converter-questions/23521/18 "2008-12-18T14:28:00Z")
> Check your owners manual. If you are close to the recommended replacement interval for the oxygen sensors, I would start there. I have never seen a maintenance schedule that recommended replacing Oxygen sensors as routine maintenance. Are there really cars made that have that listed in the owner’s manual?