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2000 Volks PAssat GLX 5sp V6 2.8L. engine code: P0421 warm up catalyst below threshold (bank 1) it was a manifold exhaust leak on the driver side. I replaced the gasket and there isn't leak after the service. is that leak related to the code? also, what should I do to fix the code P0421? thanks

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In plain terms this code (P0421) indicates the Catalytic converter is worn out and is no longer cleaning up the exhaust enough to pass the computers internal self testing that goes on all the time while the engine is running and hot, as to the exhaust leak, yes that could have set the code, what I would do at this point is clear the code and see what happens,there is a slight chance that the cat monitor (looks like an O2 sensor) located to the rear of the catalytic converter is not functioning properly, but that is seldom the cause. So clear the code and drive it for a week, if the code doesn't reset u are done, if it does the cat will need replacing.

Posted on Jul 30, 2010

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I found codes on VW's however,there is a defined one for P0420 and P0422. !@@#$ However here is a link for the breakdown of the code.
P is power train.P0 is some government required code.And the 4 relates to additional emission control.
http://www.bentleypublishers.com/tech/vw/vw.dtc.table.htm
Here is a link that will hopefully reset the system.A neighbor had to do something similar to this to eliminate a problem.It happened when he disconnected the battery.
http://www.troublecodes.net/VW/
Also just for your information,there are so many little things that could cause a check engine light to come on,just make sure you have water,oil and fluids unless it is an issue where you live due to vehicle inspection.Good luck and please reply if you have problems or if you just want to say it worked.It kind of looks like on the sites that they are pushing you to buy their diagnostic tool.Some auto parts stores will run a free computer check too.Just call around and ask.Autozone does it if it is in your state.

Posted on Jul 30, 2010

  • Greg McCarthy Jul 30, 2010

    The second link tells you how to reset the system.If your gasket fixed it,it should erase.Since I could not find the code on VW's official site,you may have to call a dealer and ask.Good luck!

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2002 mazda mpv sputtering


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.

Mar 04, 2014 | 1998 Toyota Corolla

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

1 Answer

03 santa fe code p0421 for warm up catalyst below bank 1is it converter sensors whats bank 1 converter location compared to bank 2 is there 2 banks or converters would it be upstream or downstream if it...


If the engine is a V6 (2.7 or 3.5 lit), bank 1 is next to the firewall (right hand) when facing the back of the engine.
If the engine is a 4 cly (I4), there is only one bank and is designated Bank 1 (exhaust manifold).

The catalyst to which the code refers is the UPSTREAM, and there is only ONE upstream cat for any bank.

Clue: Two upstream O2 sensor and two downstream O2 sensors - one before the CAT and one after the CAT. the downstream O2 sensors are identical to their upstream sisters. The only reason for the DOWNstream sensor is to monitor the CAT efficiency (threshold).

The catalyst on either bank is essentially the exhaust manifold which houses the CAT... it is the only CAT to which the code P0421 applies.

Hope that helped

Feb 06, 2011 | Hyundai Santa Fe Cars & Trucks

2 Answers

Check engine light on, code reads p0420


Hi and welcome to FixYa!

Code p0420 means Catalyst System Efficiency Below Threshold (Bank 1). This will surely needs attention to resolve the problem.

Hope this helps and thank you for using FixYa! Have a good one!

Jan 26, 2011 | 1999 Buick Century

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

1 Answer

How about when u have 2 catalytic converters in the same bank 1.?


If you have more than 60K miles start by replacing the Oxygen sensor(s) that is(are) installed after the catalytic converter(s). 
P0421: Warm up catalyst efficiency below threshold. This code means that the computer is detecting the catalyst not warming up to full function quickly enough based on information from the post cat O2 sensor. 

Good luck and hope this helps. 

Aug 21, 2009 | 2001 Hyundai Sonata

1 Answer

Three trouble codes


Trouble Code: P0421


Catalyst Efficiency Below Normal (Bank 1)

Possible Causes:

Air leaks at the exhaust manifold or in the exhaust pipes
Catalytic converter is contaminated, damaged or has failed

Front HO2S and/or the rear HO2S is loose in the mounting hole

Front HO2S older (aged) than the rear HO2S (HO2S is lazy)

Front HO2S or rear HO2S is contaminated with fuel or moisture


Trouble Code: P1173

HO2S-21 (Bank 2 Sensor 1) Circuit Malfunction

Possible Causes:

Base engine mechanical fault affecting one or more cylinders

EVAP Purge valve stuck or the hoses to the valve are reversed

Fuel metering fault (fuel injector sticking open or leaking)

Fuel pressure too low or too high, fuel supply contaminated

HO2S element is contaminated or the HO2S heater has failed

PCV system has air leaks at the valve or related hoses



Trouble Code: P0174
Adaptive Fuel Trim Too Lean (Bank 2)

Possible Causes:

Vehicle driven low on fuel or until it ran out of fuel

One or more injectors restricted or pressure regulator has failed

Fuel delivery system supplying too much or too little fuel during cruise or idle periods (e.g., faulty fuel pump, or dirty fuel filter)

Air leaks after the MAF sensor, or air leaks in the PCV system

Air leaks at the EGR gasket, or at the EGR valve diaphragm

Exhaust leaks before or near where the front HO2S is mounted

HO2S is contaminated, deteriorated or it has failed

Fuel control sensor is out of calibration (i.e., ECT, IAT or MAP)

Base engine -mechanical- fault affecting one or more cylinders

May 18, 2009 | 2001 Mazda MPV

1 Answer

Fault code P0421


Aicux...I had the same problem with a Mitsubishi Montero Sport. The code refers to Warm up Catalytic Converter below threshold (Bank 1) which means the two oxygen sensors before and after the cat closest to the engine are showing a variance that is outside specifications. Bank 1 is on the side of cylinder 1.

I researched and found a cause that was NOT in the list of the usual causes. Generally, this code can be caused by the following:

1 Catalytic converter defective
2 Engine Misfire or similar
3 Large vacuum leak
4 Engine oil leakage into exhaust -valve guide seals, piston rings


I have learned to always look for the simplest solution before paying big bucks for things like catalytic converters, oxygen sensors, etc. I discovered my passengers side manifold was cracked. Took off the heat shield and could see the black residue from exhaust escaping the crack. Got a used manifold from partshotlines.com for $65 and installed it. Reset the code with my OBD-II device and code hasn't returned! Problem solved.

Not sure if this is what's wrong with your, but suggest you chek the simply stuff first. Good luck.



Sep 05, 2008 | 2000 Mazda MPV

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