Question about 2002 Mitsubishi Lancer

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Trouble code p0421 could this be a sensor - 2002 Mitsubishi Lancer

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A bad cat, exhaust leak, loose sensor, bad engine controller are the potential causes.
Good luck.

Posted on Nov 06, 2010

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Posted on Jan 02, 2017

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SOURCE: mitsubishi pinin fault code P0421

yes this is your catalytic convertor is clogged you have to change before is damages ur o2 sensors

Posted on Feb 12, 2010

consaka
  • 661 Answers

SOURCE: 2 trouble code p0421 and p0421 pd

I believe this has to do with your catalytic converter. Sounds like it might be getting old. The older they get the slower they are to respond. this is due to contamination. Same is true for your Oxygen sensors.

Posted on Apr 03, 2010

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Is it possible to get a P0421 code from the OBD computer when the engine light is not on?


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.

May 06, 2014 | Mitsubishi Galant Cars & Trucks

2 Answers

P0421 CODES AND C1201


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.

Apr 24, 2014 | Toyota Avensis Cars & Trucks

1 Answer

P0421 code


"FWIW, according to the Mazda factory service manual, the P0421 code indicates "Warm up catalyst system efficiency below threshold".

The DETECTION CONDITION for this code indicates "Number of heated oxygen sensor (rear) inversion becomes closer to that of heated oxygen sensor (front)".

POSSIBLE CAUSES are:

Warm up three way catalytic converter deterioration
Leakage exhaust system
Heated oxygen sensor (front) malfunction
Heated oxygen sensor (rear) malfunction
Mass air flow sensor malfunction
Throttle position sensor malfunction
Vehicle speed sensor malfunction"
I copied the above from a discussion group on the PO421 code. The code can be caused by any of the above listed problems. The vehicle should be further inspected and diagnosed, so you do not have components replaced that do not need to be replaced.

Apr 16, 2014 | 1998 Mazda 626

1 Answer

P0421 code bank 1 warm-up efficiency below limit


P0421 code is that the cat. converter is below efficiency. 99 per cent o the time the cat. needs to be changed. but if you have a scan tool watch both bank 1 O2 sensor 1 and bank 1 sensor 2.
cold they should be almost the smae but when its at operating temp, and running down the road at crusie speed the frt o2 should switch rapidly between .150 mv. and .850 mv. and the rear o2 should read about .600 mv. if they read the same the cat is ng and will have to be replaced.

Oct 28, 2013 | 2001 Mazda Millenia

1 Answer

Will not pass smog code p0421 what is this


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
Possible SolutionsMeasure 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 sensormag-glass_10x10.gif while you're at it.

Feb 27, 2011 | Mitsubishi Lancer Cars & Trucks

1 Answer

2 trouble code p0421 and p0421 pd


I believe this has to do with your catalytic converter. Sounds like it might be getting old. The older they get the slower they are to respond. this is due to contamination. Same is true for your Oxygen sensors.

Apr 03, 2010 | 2002 Mitsubishi Galant

1 Answer

Mitsubishi pinin fault code P0421


yes this is your catalytic convertor is clogged you have to change before is damages ur o2 sensors

Feb 12, 2010 | 2001 Mitsubishi Montero

2 Answers

I am getting a P0031, P1512, & P0421 code


P0031 - most likely pointing to a failed O2 sensor (bank 1 sensor 1 is located before the catalytic converter)

P0421 - failed catalytic converter or a failed O2 sensor

P1512 - intake manifold shutter valve is stuck - may be caused by the O2 sensor, but may not

I recommend replacing your O2 sensor first and see what happens

Sep 18, 2009 | 2001 Mazda MPV

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