What is engine code p0420

P0420 Catalyst System Efficiency Below Threshold
Diagnose P0420 Catalytic Coverter Code

0 2 sensor near the catalytic converter or

replace the catalytic converter

The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar.

Read more at: https://www.obd-codes.com/p0420
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https://www.obd-codes.com/p0420

Got it scanned and it's P0420: Catalyst efficiency below thresholdbank 1. They said it could be a bad catalytic converter or oxygen sensor. I borrowed a scanner and tried to measure the oxygen sensor readings over time.Sep 8, 2011


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

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P0420 Error Code: Catalyst System Efficiency Below ...

www.obd-codes.com/p0420
P0420 OBD-II Trouble Code. Technical Description. Catalyst System Efficiency Below Threshold (Bank 1). What does that mean? This diagnostic trouble code ...

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

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Here is a tutorial on P0420 code fix catalyst efficiency below threshold How To Diagnose a p0420 code ...

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

• P1519 is what's causing the P0420. If the Variable Induction Control Actuator is stuck closed, it would cause a rich condition which will burn up the catalytic converters. get it checked asap.

P0420 isnt a misfiring code; this code P0420 is refer at Catalyst System Efficiency Below Threshold (Bank 1).

Feel free to contact us if you need additional details to volve it clicking the link.

http://www.obd-codes.com/p0420

TSB Number: 3316 NHTSA Number: 10017210 TSB Date: n/a Date Added to File: October 27, 2005 Failing Component:Electrical System Summary:Diagnostic trouble code P0420 may set on low mileage vehicles, or shortly after catalytic converter replacement
TSB Number: 3316 NHTSA Number: 10017210 TSB Date: n/a Date Added to File: October 27, 2005 Failing Component:Electrical System Summary:Diagnostic trouble code P0420 may set on low mileage vehicles, or shortly after catalytic converter replacement
there is a service bulletin for this.

http://www-odi.nhtsa.dot.gov/cars/problems/tsb/results.cfm?start=1&SearchType=DrillDown&type=VEHICLE&year=2005&make=CHEVROLET&model=COBALT&vehtype=PC&typenum=1&component_id=0&summary=true

I'm not sure you understand the difinition of OBD2 fault code P0420, it means that Catalytic converter in the exhaust that is connected to the engine cylinder bank that contains number one engine cylinder has fallen below the a allowed threshold of cleaning pollunts from the engines exhaust stream. I would be more specific but you have not given model or year of the Mercury you have.
Here is the full difinition of OBD2 fault code P0420 from the factory service information system.


P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

Possible causes - Three way catalyst converter worn out
- Intake air leaks
- Fuel injectors may be faulty
- Fuel injector leaks
- Spark plugs may be faulty
- Improper ignition timing
- Engine Control Module

CODE PO420 CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD BANK I * CODE PO325 KNOCK SENSOR NO.1 CIRCUIT MALFUNCTION BANK NO.1 OR SINGLE SENSOR

misfiring can cause a P0420 code.
I would recommend a set of honda plug wires and plugs if the P0420 code returns.
I have used bolt in aftermarket bolt in catalytic converters but don't remember the brand name they fit ok and i have had 1 or 2 return with a P0420 code out of about 20. I have never replaced the oxygen sensor on a civic like yours.
I always fix the misfire problems, reset the computer, and have the customer drive it and see if the code p0420 returns. 50% don't have the P420 code return. drive it and see what happens and go from there.

P0420 and P0430 are codes related to the catalytic converter effeciency. The catalyst will need to be replaced $$.