Error code p0421 - 2002 Mitsubishi Lancer

Yes it is and it would mean that the problem that caused the P0421 has either been corrected or is intermittent and is no longer in the state causing the failure. P0421 is a code for Warmup Catalyst Efficiency so there. Like be an intermittent problem with an O2 sensor or the catalytic converter may be starting to clog.

C1201 error code means that you have some problem in engine control system.

Possible causes for P0421 error

• Warm Up Three Way Catalytic converter deterioration or malfunction
• Exhaust system leaks
• Loose front or rear HO2Ss
• Faulty front heater O2 sensor
• O2 sensors harness is open or shorted
• O2 sensors poor electrical connection

The P0421 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem.

Error Code: P0421
Description:
Warm Up Catalytic Converter, Bank 1 - Efficiency Below Threshold
Possible Cause:
Warm Up Catalyst Bank 1 faulty.
Possible Solutions:
Check Warm Up Catalyst Bank 1 - Set Readiness.
Replace Warm Up Catalyst Bank 1.

code P0421 may mean that one or more of the following has happened:

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

Possible Solutions

P0421: Warm Up Catalyst Efficiency Below Threshold (Bank 1).

This could apear because of a bad O2 sensor on the catalytic converter on bank 1.

Or The catalytic converter is no longer functioning properly.

Hope this helps you. Good luck bro

Code - P0421 text as follows:

WARM UP CATALYST BELOW THRESHOLD - BANK 1 usually this is caused be poor spark wires or plugs. If the ignition system is in poor condition or recently repaired because of misfire it could indicate that the front converter is now burnt up and requires replacement.
First pls check if ur car needs a tune up? if not done since long (3yrs/60K miles), do the tune up and see if it helps. or else u will need to do as explained above.

my 2001 mazda 626 V-6 have a error code p0421 & P0421 so how do i fix it. tell me the causes and the solution

PO421:Warm Up Catalyst-below threshold (bank #1) CEL

A code P0421 may mean that one or more of the following has happened:
* The catalytic converter is no longer functioning properly
* An oxygen sensor is not reading (functioning) properly
* A sparkplug is fouled up

How to...

Hope helped (remember rated this help) Good luck.

Hi,

So you have a P0421.

A code P0421 may mean that one or more of the following has happened:

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

As far as running conditions if it performs normally, you most likely need a catalytic converter. The good part of this is there shouldn't be any abnormal running conditions, so it should be fine unless the engine is running very rich for some reason. (it will usually smell badly when this happens) However, on rare occasions the cat can get hot and melt down causing an exhaust restriction..bad gas mileage, low power, and possible fire potential, but most likely this is not the case. (this is generally speaking here and covering all the bases... )

The most common thing with P0421 that the fuel injection computer detects that the cat is not performing to federal specs an need to be replaced. You will need to have it fixed before your vehicle inspection.
Good luck and I hoped this helped you.