Question about 2003 Mitsubishi Eclipse Coupe

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Code po421 how to fix

I have a 2003 eclipse 2.4 liter. Got a code po421 when i took it in for inspection.(po421 is the warm up catalyst efficiency below threshold-bank-1)How do i find out (1- what that is)( 2- how to fix it.)

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You have the same engine as my 2003 Galant, this should help... http://www.alldatadiy.com/alldata/AFI~V11366605~C40797~R0~OD~N/0/89012112/98644464/98644470/110938985/34853741/34857029/34857030/34857663/122915129/135964338/135975025

Posted on Mar 01, 2009

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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

Code p431 and p421


P421=Warm up catalyst system efficiency below threshold, bank 1
P431=Warm up catalyst system efficiency below threshold, bank 2
Sounds like you may have clogged or damaged catalyst converters or bad 02 sensors.
Those codes I think are taking from after the catalyst by the sensors in the exhaust pipes. Be careful taking it to a mechanic for further checking since the catalyst converters are not cheap through them. If you need to replace the converters, shop around and get prices on aftermarket parts. Don't be ripped off by a hungry mechanic or especially a dealer.

Aug 17, 2013 | 2006 Mitsubishi Eclipse

1 Answer

Po421


po421 catalytic converter code [warm up catalyst efficiency below threshold bank 1] means the o2 sensor is detecting low oxygen in exhaust problem can be cat conv going bad---o2 sensor faulty-and or bad spark plug ....as to the p0441 evap system[-evap emissions control system incorrect purge flow ] this is a system code meaning any part of the evap can have problem will need to check the fuel lines vapor lines for damage or breaks-check purge valve -purge valve solenoid- canister- and vacuum lines

Apr 10, 2013 | 2003 Mitsubishi Lancer

1 Answer

03 mazda mpv didn't pass inspection because of fault PO431?


Have the catalytic converter and your O2 sensor checked.

Apr 05, 2013 | 2003 Mazda MPV

1 Answer

Where should i find this sensor P0342?


EXHAUST RELATED ERROR CODES

There are 711 possible PO generic DTC error codes. Only 7 of the 711 codes are exhaust related.

PO401: Insufficient EGR Flow

PO402: Exhaust Gas Recirculation (EGR) Excessive Flow Detected

PO410: Secondary Air Injection System Malfunction

PO420: Catalyst System Efficiency Below Threshold (Bank 1)

PO421: Warm-Up Catalyst Efficiency Below Threshold (Bank 1)

PO430: Catalyst System Efficiency Below Threshold (Bank 2)

PO431: Warm-Up Catalyst Efficiency Below Threshold (Bank 2)

THINGS TO ASK YOURSELF OR YOUR CUSTOMER

Have there been any driveability or performance issues with the vehicle, have there been any recent repairs or tune-up work performed, if so was the check engine light reset and were the codes recorded on previous repair orders.

Do not rely on scan tool data alone. In most applications, the customer will have the check engine light reset prior to repair. If the original cause of converter failure is intermittent, only the catalyst failure code may show up (masking the original reason for converter failure).

Nov 04, 2012 | Chevrolet Epica Cars & Trucks

1 Answer

What does a po430 code mean on a mercury cougar


EXHAUST RELATED ERROR CODES

There are 711 possible PO generic DTC error codes. Only 7 of the 711 codes are exhaust related.

PO401: Insufficient EGR Flow

PO402: Exhaust Gas Recirculation (EGR) Excessive Flow Detected

PO410: Secondary Air Injection System Malfunction

PO420: Catalyst System Efficiency Below Threshold (Bank 1)

PO421: Warm-Up Catalyst Efficiency Below Threshold (Bank 1)

PO430: Catalyst System Efficiency Below Threshold (Bank 2)

PO431: Warm-Up Catalyst Efficiency Below Threshold (Bank 2)

THINGS TO ASK YOURSELF OR YOUR CUSTOMER

Have there been any driveability or performance issues with the vehicle, have there been any recent repairs or tune-up work performed, if so was the check engine light reset and were the codes recorded on previous repair orders.

Do not rely on scan tool data alone. In most applications, the customer will have the check engine light reset prior to repair. If the original cause of converter failure is intermittent, only the catalyst failure code may show up

Nov 04, 2012 | Cars & Trucks

2 Answers

What are codes P1492, P0421 & P0431 on the 2002 Mazda Millenia?


po421 warm up catalyst efficiency below threshhold bank 1, 431 same on bank 2..

Feb 08, 2010 | 2002 Mazda Millenia

3 Answers

I have a 2003 MPV with trouble code PO327 and PO431. What do these mean? Thank you.


P0327 Knock Sensor 1 Circuit Low Bank 1 or Single Sensor
P0431 Warm Up Catalyst Efficiency Below Threshold Bank 2


Sep 28, 2009 | 2003 Mazda MPV

1 Answer

I have a 2003 mitsubishi esclispe spyder gt


Basically this means that the oxygen sensor downstream of the catalytic converter on bank 1 is detecting that the converter is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system

Apr 28, 2009 | 2003 Mitsubishi Eclipse Spyder

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