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Eric, Automotive Repair Shop Manager
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02 VW Jetta - I have a code P0420 - Catalyst system efficiency

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02 VW Jetta - I have a code P0420 - Catalyst system efficiency below threashold - Bank1

What is this referring too?

Hi,

 

Fault code P0420 is for catalyst below efficiency threshhold. This normally means a faulty catalytic convertor.

 

The catalytic convertor is covered by the Federal Emissions Warranty for 8yrs or 80,000 miles, so if you are under the mileage the convertor will be replaced under warranty at the dealership.

 

there is a TSB(technical service bulletin) on this:

 

Emissions - MIL ON/DTC P0420/Cat Converter Rattling
Notes

26 07 05

Sept. 5, 2007

(NNN) NNN-NNNN/p>

Vehicle Information

Condition

MIL is ON and/or Catalytic Converter is Rattling

MIL is ON, DTC P0420 is stored and/or catalytic converter rattling.

Technical Background

The expansion mat in the original part can erode prematurely, causing the converter to rattle and/or MIL ON.

A new part was designed to fix this concern.

Production Solution

Repair identified after production was completed.

Service

The above condition MAY be covered by the Catalytic Converter Limited
Extended Warranty, see Warranty Service Circular VWA-07-20.

 

Prior to replacing a catalytic converter under the Catalytic Converter Limited Extended Warranty, perform the following procedure:

^Check the engine oil level.

 

Oil level MUST be correct.

If overfilled,

^Oil level should be adjusted to proper level prior to continuing.

 

Adjusting oil level is NOT covered by Warranty.

Is Catalytic Converter Rattling?

^Inspect the catalytic converter for a broken or deteriorated monolith (honeycombed interior element).

 

If catalytic converter is NOT rattling:

^Go to Interrogating DTC memory (below).

 

If catalytic converter is rattling:

^Visually inspect vehicle underbody to ensure that converter was not damaged from outside influence such as dented converter housing, etc.

 

If signs of external damage to catalytic converter exist:

The cost of replacement catalytic converter is NOT covered by warranty.

^Continue to Interrogating DTC memory (below).

 

Interrogating DTC Memory

^Interrogate Diagnostic Trouble Code (DTC) memory (DO NOT erase DTCs).

 

Required Documentation

^For Analysis and Warranty purposes, you MUST make (and store) print-outs of the DTC memory, including:

 

Address 01 fault memory including ECM information.

"OBD" freeze-frame modes 2 and 6.

Tip:

For OBD, see ElsaWeb, Repair Manual - Fuel Injection & Ignition 2.0 Liter 4Cyl. 2V Generic Scan Tool.

Steps for printing "OBD" from the touch screen:

^Select "OBD".

 

^Select "mode 2".

 

^Select all PIDS displayed (use scroll bar if necessary).

 

^Select right arrow key to display results.

 

^Select "print", and then save result.

 

^Save results for modes 2 and 6.

 

^Print self diagnosis log.

 

Address 01 Measuring Value Block (MVB) 46.

Tip:

The DTC codes present will need to be erased before the test will run in MVB 46.

Is DTC P0420 (Catalyst System Efficiency Below Threshold, Bank 1) Stored?

^Check if DTC P0420 (Catalyst System Efficiency Below Threshold, Bank 1) is stored.

 

^Check if DTCs from Table are stored.

 

If catalytic converter is NOT rattling and DTC P0420 and any DTC(s) from table are stored:

^Proceed to "DTCs in table are stored" (see below).

 

If catalytic converter is rattling and any DTC(s) from table stored:

^Proceed to "DTCs in table are stored" (see below).

 

If catalytic converter is NOT rattling and P0420 is the only DTC stored:

^Proceed to "Replace catalytic converter" (see below).

 

If catalytic converter is rattling and P0420 is the only DTC stored.

No DTCs are stored:

^Proceed to "Replace catalytic converter" (see below).

 

DTCs in table are stored:

The reason for DTC(s) from Table MUST be corrected (possibly at customer expense) prior to potential catalytic converter replacement.

With other DTC(s) corrected:

If catalytic converter is rattling:

^Proceed to "Replace catalytic converter" (see below).

 

If catalytic converter is NOT rattling:

^Erase all DTC(s) and set readiness code.

 

If complete readiness code cannot be set due to the catalyst diagnosis monitor in display group 46 not resetting:

^Proceed to "Replace catalytic converter" (see below).

 

If complete readiness code can be fully set:

^Return vehicle to the customer without replacing catalytic converter.

 

If vehicle was returned to the Customer (without converter replacement) and Customer returns with DTC P0420 stored again:

^Proceed to "Replace catalytic converter" (see below).

 

Replace catalytic converter

^Erase all DTC(s) and set readiness code.

 

Warranty

Catalytic Converter Limited Extended Warranty:

^For Details, see Warranty Service Circular VWA-07-20.

 

Required Parts and Tools

When replacing any catalyst, your VIN may be required to ensure the correct part is ordered (check with your Parts Dept.).

Parts submission:

If catalytic converter is on parts submission:

^Attach copies of all supporting documentation (including print-outs) required when sending parts to Warranty Test Center.

 

Tip:

Claims for Catalytic Converters (which are on submission) that are shipped to the Warranty Test Center without print-outs (including freeze frame data) may be denied.

Additional Information

All part and service references provided in this Technical Bulletin are subject to change and/or removal.

Always check with your Parts Dept. and Repair Manuals for the latest information

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