P0421 Error Code - 2010 Mazda3 - Help?

[tommyx2]

Hi guys,

I have a stock 2010 mazda3, and it has an error code of P0421 ( Warm Up Catalyst Efficiency Below Threshold (Bank 1) ).
I pulled it from my OBDII reader.

My question is, do you guys have any recommendations of dealerships/shops that can look at this error?
I've tried resetting the ECU by cutting the battery power, and also resetting it by the OBDII reader. The code re-surfaces after awhile of driving.
I don't notice any performance changes and the mpg hasn't changed much. Any help would be appreciated.

Thanks!

[Hyperion]

• The catalytic converter is no longer functioning properly
• An oxygen sensor is not reading (functioning) properly
• A sparkplug is fouled up

Measure the voltage at the oxygen sensor on Bank 1 (the rear sensor, or the sensor after the converter). In fact, it would be a good idea to test each oxygen O2 sensor while you're at it. One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into

[js593]

• The catalytic converter is no longer functioning properly
• An oxygen sensor is not reading (functioning) properly
• A sparkplug is fouled up

Measure the voltage at the oxygen sensor on Bank 1 (the rear sensor, or the sensor after the converter). In fact, it would be a good idea to test each oxygen O2 sensor while you're at it. One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into

hyperion,

Would you happen to have the figures (voltage and reading wise) for the O2 sensors? I'm currently not hooked up to Mitchel, but that would definitely help!

[Hyperion]

Nope. Sorry

[tommyx2]

Just an update, Replaced my O2 sensors and the code went away. it's been approximately 1000kms now...