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What means catalyst Efficiency below normal - Cars & Trucks

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Mike King

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Posted on Dec 14, 2016

Mike King

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This code occurs when the upstream & downstream O2's hold similar readings; and which indicates to the computer that the catalyst isn't efficient/not cleaning Nox. With a scanner one can determine by looking at both O2's @the sametime rather they're switching or not at similar speeds. Normally a bad Upstream O2 sensor will set a code, whereas a bad downstream O2 sensor may not set a code or the code may come in the form of catalyst efficiency below threshold; and you'll come to find that sensor is either switching extremely slow or not at all. When an upstream sensor goes bad it will often switch at a slower rate thus mimicking the downstream O2 sensor; of which is normally a slower switching sensor; but here again slow switching Upstream O2 sensor or a malfunctioning altogether Upstream O2 sensor will cause a code to be set independently of a catalyst efficiency below threshold code or in tandem with.????

Claude Kayser

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Posted on Jan 26, 2016

Claude Kayser

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Catalyst efficiency below threshold

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I've had a trouble code( P0420) code come up,

Catalyst System Efficiency Below Threshold (Bank 1). OK, now tell me that again in plain English please.... let's break it down: the catalyst system being referred to is your three-way catalytic converter; so the catalytic converter is not working properly (i.e. it's not efficient). Bank 1 refers to the side of the engine which contains cylinder #1. On inline engines such as 4 & 5 cylinder engines, there is only one bank. So, to really simply things let's just say that the efficiency of the catalytic converter and/or exhaust pipe and/or O2 sensor is not so great. Hope this helps.

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Mar 09, 2013 • Cars & Trucks

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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

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Nov 04, 2012 • Cars & Trucks

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1996 taurus p420 code

The P0420 means Catalyst System Efficiency Below Threshold (Bank 1), and the P0430 means Catalyst System Efficiency Below Threshold (Bank 2).
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ECU unlock immobilizer tool

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Sep 17, 2012 • 1996 Ford Taurus

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What do these codes mean ? po430 po420 po306 for mercury cougar 1999

P0430 code is(catalyst efficiency below threshold on bank 2)
P0420 code is((catalyst efficiency below threshold on bank 1)
P0306 code is(cylinder 6 misfire detected)

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Dec 13, 2011 • 1999 Mercury Cougar

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THE CODE READS ER0422

P0422 Main Catalyst Efficiency Below Threshold (Bank 1) is what the code means. That is indicating you have a catalytic converter problem but in reality it is normally a Downstream O2 Sensor problem. replace the O2 Sensor and that should resolve the issue.

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Sep 22, 2010 • 2004 Ford Focus

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2answers

I have a 2001 VW golf that I just bought. It passed smog checks no problem. But now the Engine Light is "ON" and the guy at the shop told me that the code is 420. What is code 420?

if the code is p0420
it means
catalyst system efficiency below threshold
(cylinder bank no.1)

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Aug 21, 2010 • 2001 Volkswagen Golf

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1997 Mercury Mountaineer What is Catalyst Efficiency Below (Bank

it means the catalyst is worn out, the efficiency is monitored by sensors, when the Cat falls below a certain reading or "threshold" the code is generating telling u that u need a new catalytic converter.

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Feb 18, 2010 • 1997 Mercury Mountaineer

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Code PO42O and PO43O ? Anyone know what they

The meaning of: P0420 Catalyst System Efficiency Below Threshold on Bank 1 P0430 Catalyst System Efficiency Below Threshold on Bank 2

Basically the Oxygen sensors ( one before and one after the catalytic converter ) have abnormal readings from the exhaust. Further diagnosing will need to be done by a mechanic to find the source of the problem. The possibilities could be the O2 sensors themselves, a leak in the exhaust manifold, a bad catalytic converter, and etc.

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Nov 14, 2009 • 2002 Toyota RAV4

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Vsc and check engine light is on . Had it read and code p0420 came up. Autozone said it could be an air leak in exhaust, AF sensor error, fuel system fault or faulty catalytic converter. Is there a cheap...

DTC P0420: Catalyst System Efficiency Below Threashold (Bank 1)

The ECM uses sensors mounted before and after the three-way catalyst (TWC) to monitor its efficiency. The first sensor, and Air Fuel ratio (A/F) sensor, sends pre-catalyst A/F ratio information to the ECM. The second sensor, a heated oxygen sensor (O2S), sends post-catalyst information to the ECM. The ECM compares these two signals to judge the efficiency of the catalyst and the catalyst's ability to store oxygen. During normal operation, the TWC stores and releases oxygen as needed. The capacity to store oxygen results in a low variation in the post-TWC exhaust stream as shown below.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor slowly switches between RICH and LEAN. If the catalyst is deteriorated, the waveform will alternate frequently between RICH and LEAN. As the catalyst efficiency degrades, its ability to store oxygen is reduced and the catalyst output becomes more variable. When running the monitor, the ECM compares sensor 1 signals (A/F sensor) over a specific amount of time to determine catalyst efficiency. The ECM begins by calculating the signal length for both sensors (for the rear oxygen sensor, the ECM uses the output voltage signal length). If the oxygen sensor output voltage signal length is greater than the threshold (threshold is calculated based on the A/F sensor signal length), the ECM concludes that the catalyst is malfunctioning. The ECM will turn on the MIL and a DTC will be set.
Hope this helps :)

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Oct 19, 2009 • 2005 Toyota Highlander

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Catalyst Efficiency Below Threshold (Bank One)

what is catalyst efficiency below threshold ( bank 1 ) mean?

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Dec 12, 2008 • 2005 Nissan Maxima

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What means catalyst Efficiency below normal - Cars & Trucks

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Mike King

Claude Kayser

civic - Check Engine code P0420 Catalyst efficiency below ...

P0420 Error Code: Catalyst System Efficiency Below ...

P0420 Code Fix How Its Done Catalyst Efficiency Below ...

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What do these codes mean ? po430 po420 po306 for mercury cougar 1999

THE CODE READS ER0422

I have a 2001 VW golf that I just bought. It passed smog checks no problem. But now the Engine Light is "ON" and the guy at the shop told me that the code is 420. What is code 420?

1997 Mercury Mountaineer What is Catalyst Efficiency Below (Bank

Code PO42O and PO43O ? Anyone know what they

Vsc and check engine light is on . Had it read and code p0420 came up. Autozone said it could be an air leak in exhaust, AF sensor error, fuel system fault or faulty catalytic converter. Is there a cheap...

Catalyst Efficiency Below Threshold (Bank One)

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What means catalyst Efficiency below normal - Cars & Trucks

2 Answers

Mike King

Claude Kayser

civic - Check Engine code P0420 Catalyst efficiency below ...

P0420 Error Code: Catalyst System Efficiency Below ...

P0420 Code Fix How Its Done Catalyst Efficiency Below ...

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Related Questions:

I've had a trouble code( P0420) code come up,

What does a po430 code mean on a mercury cougar

1996 taurus p420 code

What do these codes mean ? po430 po420 po306 for mercury cougar 1999

THE CODE READS ER0422

I have a 2001 VW golf that I just bought. It passed smog checks no problem. But now the Engine Light is "ON" and the guy at the shop told me that the code is 420. What is code 420?

1997 Mercury Mountaineer What is Catalyst Efficiency Below (Bank

Code PO42O and PO43O ? Anyone know what they

Vsc and check engine light is on . Had it read and code p0420 came up. Autozone said it could be an air leak in exhaust, AF sensor error, fuel system fault or faulty catalytic converter. Is there a cheap...

Catalyst Efficiency Below Threshold (Bank One)

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I've had a trouble code( P0420) code come up,

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