P0420 on HONDA PILOT — Catalyst System Efficiency Below Threshold Bank 1

Q: "What does P0420 mean on a HONDA PILOT?"

"P0420 indicates: Catalyst System Efficiency Below Threshold Bank 1. This is a emission controls code. 9 HONDA PILOT owners have reported this to NHTSA."

Q: "What are the most common causes of P0420 on HONDA PILOT?"

"Based on 9 NHTSA reports, the most commonly cited components are: Engine, Fuel/Propulsion System, Engine,Fuel/Propulsion System. These percentages are based on the component field in owner complaints."

Q: "Is P0420 serious on my HONDA PILOT?"

"Of 9 NHTSA reports for this code on HONDA PILOT, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic."

Q: "What should I do if my HONDA PILOT shows P0420?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

What P0420 Means on Your HONDA PILOT

P0420 is a diagnostic trouble code indicating: Catalyst System Efficiency Below Threshold Bank 1. This code relates to the emission controls system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

9 HONDA PILOT owners have reported this issue to NHTSA across model years 2016-2017. Most reports come from the 2016, 2017 model years.

Real HONDA PILOT Owner Reports

Source: NHTSA Complaints Database

"My vehicle suffered a catastrophic failure of the exhaust and engine systems directly caused by the defective fuel injection system identified in Service Bulletin 20-100."

— 2016 HONDA PILOT owner · ENGINE,FUEL/PROPULSION SYSTEM · Filed 05/01/2025

"Check engine light on emissions system problem and transmission system problem, there is loss power of engine light, after 2 gear transmission feel like it jerks I don't have save to drive my car, i would like to request a recall to be inspected and repair by warranty of Honda because my car is de"

— 2016 HONDA PILOT owner · ELECTRICAL SYSTEM,ENGINE · Filed 05/26/2025

"My car got recall from Honda on:  P0420 (rear bank catalyst system efficiency below threshold [bank 1])  P0430 (front bank catalyst system efficiency below threshold [bank 2])  P0300-P0306 (misfire)  P219A (air-fuel ratio variation of cylinder [bank 1, rear bank])  P219B (air-fuel ratio variati"

— 2016 HONDA PILOT owner · FUEL/PROPULSION SYSTEM,FORWARD COLLISION AVOIDANCE · Filed 03/15/2023

"Honda has a known issue with its emissions. A warranty extension Service Bulletin 22-002 has been issued to replace fuel injectors up to 10 yrs 150,000 miles but they do not identify other malfunctioning components that also need replacement."

— 2016 HONDA PILOT owner · ENGINE · Filed 07/05/2022

"Our 2016 honda pilot had a check engine light for fault code p0420. dealer diagnosis was faulty fuel injectors in cylinders 2 and 3. dealer replaced all 6 fuel injectors free of charge. it seems preposterous that any of the 6 fuel injectors had failed with only 41,632 miles on the odometer."

— 2016 HONDA PILOT owner · FUEL/PROPULSION SYSTEM · Filed 11/04/2019

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

5

'16

4

'17

Common Causes on HONDA PILOT

Based on NHTSA complaint component analysis for this vehicle.

ENGINE 22.2%

FUEL/PROPULSION SYSTEM 22.2%

ENGINE,FUEL/PROPULSION SYSTEM 11.1%

ELECTRICAL SYSTEM,ENGINE 11.1%

FUEL/PROPULSION SYSTEM,FORWARD COLLISION AVOIDANCE 11.1%

What To Do Next

1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.

Frequently Asked Questions

What does P0420 mean on a HONDA PILOT? ▾

P0420 indicates: Catalyst System Efficiency Below Threshold Bank 1. This is a emission controls code. 9 HONDA PILOT owners have reported this to NHTSA.

What are the most common causes of P0420 on HONDA PILOT? ▾

Based on 9 NHTSA reports, the most commonly cited components are: Engine, Fuel/Propulsion System, Engine,Fuel/Propulsion System. These percentages are based on the component field in owner complaints.

Is P0420 serious on my HONDA PILOT? ▾

Of 9 NHTSA reports for this code on HONDA PILOT, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic.

What should I do if my HONDA PILOT shows P0420? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.