Service Engine Light

[nzalmasri]

The service engine light on my 2001 Maxima came on. The code is P0420 and it reads Catalyst efficiency below threshold, bank 1. One mechanic said it is the spark plug number 1. Other mechanic said it is the Catalytic Converter. The differance is over $200. Anyone can help? Thanks.

[vinceleto]

Originally Posted by nzalmasri

The service engine light on my 2001 Maxima came on. The code is P0420 and it reads Catalyst efficiency below threshold, bank 1. One mechanic said it is the spark plug number 1. Other mechanic said it is the Catalytic Converter. The differance is over $200. Anyone can help? Thanks.

I have the same problem same code on my 2000. It comes on and off every once in a while. My gas milage is still good. I have about 60k miles and I'm thinking about chaging the plugs.

[nzalmasri]

I changed the plugs because they are the cheapest and reset the light. I doubt if they were the real cause. The old plugs look in good condition.

[nzalmasri]

The light came on again. Anyone knows what is bank 1 and where it is located? Thanks

[habenero2002]

2000-2001 maxima need to have their computer reprogrammed by the dealer to fix this problem. Bank one is the cylinder head closest to the firewall

[nzalmasri]

Don't they charge arm and leg for that?

[gentle_big_man_4_u]

The answer to your ? is looking at the engine with the fanbelt right in front of you bank one is the left side of the motor.

[gentle_big_man_4_u]

Does anyone know why my 2001 Maxima can not be emmision tested? the tester said the cat was not ready, and my scan tool says the same thing?

[Mrbizness1]

Originally Posted by gentle_big_man_4_u

Does anyone know why my 2001 Maxima can not be emmision tested? the tester said the cat was not ready, and my scan tool says the same thing?

If the check engine light was reset recently and the vehcle hasn't been driven enough (ususlly around 25+ miles) you will get the not ready indication.
Someone told me it was to prevent people from clearing the light and going to get it inspected before the code resets the light.

[Mrbizness1]

Originally Posted by gentle_big_man_4_u

Does anyone know why my 2001 Maxima can not be emmision tested? the tester said the cat was not ready, and my scan tool says the same thing?

If the check engine light was reset recently and the vehcle hasn't been driven enough (ususlly around 25+ miles) you will get the not ready indication.
Someone told me it was to prevent people from clearing the light and going to get it inspected before the code resets the light.

[Mrbizness1]

Originally Posted by gentle_big_man_4_u

Does anyone know why my 2001 Maxima can not be emmision tested? the tester said the cat was not ready, and my scan tool says the same thing?

If the check engine light was reset recently and the vehicle hasn't been driven enough (usually around 25+ miles) you will get the not ready indication.
Someone told me it was to prevent people from clearing the light and going to get it inspected before the code resets the light.

[Nahkapohjola]

Originally Posted by Mrbizness1

...to prevent people from clearing the light and going to get it inspected before the code resets the light.

Reset clears all ECU registers which contain data to adjust for sensor characteristics. Each sensor is individual eg slightly different from others and they do age differently... Thus there must be a 'learning' period where ECU adjusts for best performance and corrective data is entered in to adjust for any biased sensor(s). The 'learning curve' contains certain speeds, rpm, temp etc requirements during various drive cycle times - check what and how via top left 'Favorite Links' -at link below.

Its not '25miles' but the factory specified different drivin conditions fulfilled to collect the data (which may become at 25miles). Check out, theres a chart howto drive this 'break in' for example after MAF cleanup/replacement. If one bypasses this teach process, the only problem possibly is longer time to get this finetuning through.

[FixUrNissan]

Ok Here is the answer to all your questions. First off , Mileage is important to know on your Maxima. If your mileage is with in 8 years or 80 Thousand Miles , a Cat Converter would be covered underwarrenty. But First the Nissan Dealer Would Probable Need to do a ECM ( Engine Control Module) Reprogram with updated Software. After the Ecm reprogram you will need to probably drive the car for at least 100 miles or so . After wards , have them Recheck your SRT's ( System Readiness Tests) To see if it complete. When Codes are erased or ecm are reprogrammed , all SRT's are cleared and the systems have to run self checks to complete. If a System can not be completed the it is safe to say there is a problem in that system . So your P0420 B1. Bank 1 The location is the side of the Engine back by the fire wall . The ECM reprogram should be covered under warranty with the 8/80 i describe in the beginning. Emissions warranty . If they say it's not. Challenge them on it, that is if your in warranty. Under 80k miles. If you have any more Questions on this , Feel Free to ask .. GL ..

[Chester86]

opcorn: Howdy folks,

Looks like its time for me to join the club also. I recently got hit with the P0430 code also. IT says its the second Cat in Bank 2. Should I just go ahead and change it out and see from there?? I will reset the ECU tonight and will check the plugs and basic diagnostics on the car later today . . just to ensure everything is OK first . . but, based on the respones I have seen . . Cat Bank 2 replacement should do the trick. Let me know what you guys think. Thanks!! Happy New YEar!!

--Chester86