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How do I know which cat is bad?

(2003 Honda Civic Hybrid)
in Grass Lake, MI on October 16, 2010
I have a 2003 HHybrid and I can smell the cat and getting the P1420 code. How do I know which cat needs to be replaced?
Displaying 1 answers & 2 comments
Popular Answer
on October 16, 2010
You need to contact to a Honda dealership with your VIN#. There is a known problem about the P1420 DTC. It could be caused by a wrong software in the ECM, so a simple software upgrade might fix this problem.
If it caused by software error, catalytic converter replacement won't fix it. You will spend $$$ on a new cat, and the code will come back.
The dealer will be able to tell if the "Service Campaign" can be applied to your car and get free software upgrade.

on December 28, 2010
can you elaborate on this? How long has this software fix been available? I have had my 03 Hybrid to the dealer a number of times in the past 2-3 years and not heard about this.

Any info would be helpful as my past experience is service guys tends play-dumb on these kind of things...
on December 28, 2010
Sure, here is the Campaign / TSB:

Campaign - PGM Update for MIL ON/DTC's P0420/P1420/P2000


June 15, 2007
Applies To:
2003-05 Civic Hybrid ULEV (KA) - ALL
2002-06 Insight With M/T - ALL

Product Update: MIL Comes On With DTC P0420, P1420, or P2000


The PGM-FI software can misinterpret sensor inputs as a deteriorated three-way catalytic converter or deteriorated NOx adsorptive three-way catalyst. If this happens, the MIL comes on with these DTCs:
^ 2003 Civic Hybrid ULEV - DTC P1420 (NOx adsorptive catalyst efficiency below threshold)

^ 2004-05 Civic Hybrid ULEV - DTC P2000 (NOx adsorptive catalyst efficiency below threshold)

^ 2002-03 Insight M/T - DTC P0420 (TWC catalyst system efficiency below threshold), or DTC P1420 (NOx adsorptive catalyst efficiency below threshold), or both.

^ 2004-06 Insight M/T - DTC P2000 (NOx adsorptive catalyst efficiency below threshold)

NOTE : This product update campaign does not apply to 2003-05 Civic Hybrid PZEV (KL) vehicles.

Not all vehicles within the affected model years are affected by this product update. To verify vehicle eligibility, you must check for at least one of these items:
^ The customer has a notification letter.

^ The vehicle is shown as eligible on a VIN status inquiry.

In addition, check for a punch mark below the first character of the engine compartment VIN. A punch mark in that location means this product update has already been completed.


All owners of affected vehicles will be sent a notification of this product update. An example of the customer notification is at the end of this service bulletin.


Update the PGM-FI software with the HDS.


HDS Software Version: 2.009.007 (Brown CD) or later.
NOTE : An incorrect HDS software version may indicate that the vehicle does not need an update.

The updated PGM-FI software program IDs and P/Ns are shown below. If any of these, or later program IDs, are the Current Program IDs displayed during the update, the software for this product update is already installed in the vehicle.

NOTE : Do not submit a warranty claim for 2003-05 Civic Hybrid PZEV (KL) vehicles. These models are not affected by this product update.

Operation Number: 125517

Flat Rate Time: 0.3 hour

Failed Part: P/N 37820-PZA-308
H/C 8182693

Defect Code: 5PF00

Symptom Code: Q4900

Template ID: 07-036A

Skill Level: Repair Technician

1. Update the ECM/PCM with the HDS and software version 2.009.007 or later. Refer to Service Bulletin 01-123, Updating Control Units/Modules.

2. Center-punch a completion mark below the first character of the engine compartment VIN:

3. For California Residents Only: Fill out a Vehicle Emissions Recall - Proof or Correction certificate, and use Q49 as the recall number. Give the certificate to your customer, and advise him or her to keep it as proof that the product update was completed. Your customer will need to submit the certificate to the DMV only if the DMV requests it. If you need more certificates, use reorder number Y0657.
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