How do I fix a p0420 code

Question 1

0 crwdns2873741:0crwdne2873741:0

crwdns2934197:0crwdne2934197:0 2006-2014 GMC Yukon crwdns2933315:00crwdne2933315:0

Nelson

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masiku 6 agoMud 29, 2026

asked masiku 6 agoMud 29, 2026 crwdns2933505:0crwdne2933505:0 Nelson

Question 2

0 crwdns2873741:0crwdne2873741:0

يظهر صوت مزعج عندما اضع المحرك على وضعية القيادة

crwdns2934197:0crwdne2934197:0 2000-2006 GMC Yukon crwdns2933315:00crwdne2933315:0

oldturkey03 857crwdns2936485:0crwdne2936485:0

crwdns2931741:0crwdne2931741:0

Mud 23, 2026

commented Mud 23, 2026 crwdns2933505:0crwdne2933505:0 oldturkey03

Question 3

1 crwdns2930801:0crwdne2930801:0

My A/C is going from hot to cold and back A/C no longer blows

2015-Present GMC Yukon crwdns2933313:01crwdne2933313:0

Shawn Frederick

crwdns2931741:0crwdne2931741:0

Mud 17, 2026

commented Mud 17, 2026 crwdns2933505:0crwdne2933505:0 Shawn Frederick

Question 4

1 crwdns2930801:0crwdne2930801:0

Windshield washer not working

2015-Present GMC Yukon crwdns2933313:01crwdne2933313:0

Jerry Wheeler 94,6crwdns2936485:0crwdne2936485:0

crwdns2931217:0crwdne2931217:0

Dzi 25, 2026

answered Dzi 25, 2026 crwdns2933505:0crwdne2933505:0 Jerry Wheeler

Question 5

0 crwdns2873741:0crwdne2873741:0

2007 Yukon 1500XL Engine Light

crwdns2934197:0crwdne2934197:0 2006-2014 GMC Yukon crwdns2933315:00crwdne2933315:0

John Stack 13

crwdns2931731:0crwdne2931731:0

Dzi 18, 2026

asked Dzi 18, 2026 crwdns2933505:0crwdne2933505:0 John Stack

Question 6

0 crwdns2873741:0crwdne2873741:0

How to replace switch on driver side seat on a 2016 Yukon

crwdns2934197:0crwdne2934197:0 2015-Present GMC Yukon crwdns2933315:00crwdne2933315:0

jayeff 540,6crwdns2936485:0crwdne2936485:0

crwdns2931745:0crwdne2931745:0

Dzi 2, 2026

marked as duplicate Dzi 2, 2026 crwdns2933505:0crwdne2933505:0 jayeff

Question 7

0 crwdns2873741:0crwdne2873741:0

How do I fix my driver side retractable mirror? Motor runs but doesn’

crwdns2934197:0crwdne2934197:0 2006-2014 GMC Yukon crwdns2933315:00crwdne2933315:0

jayeff 540,6crwdns2936485:0crwdne2936485:0

crwdns2931741:0crwdne2931741:0

Kul 15, 2026

commented Kul 15, 2026 crwdns2933505:0crwdne2933505:0 jayeff

Question 8

0 crwdns2873741:0crwdne2873741:0

Driver side mirror does not retract.

crwdns2934197:0crwdne2934197:0 2015-Present GMC Yukon crwdns2933315:00crwdne2933315:0

jayeff 540,6crwdns2936485:0crwdne2936485:0

crwdns2931745:0crwdne2931745:0

Kul 15, 2026

marked as duplicate Kul 15, 2026 crwdns2933505:0crwdne2933505:0 jayeff

Question 9

1 crwdns2930801:0crwdne2930801:0

Why does my battery go dead sometimes and sometimes it dont

2000-2006 GMC Yukon crwdns2933313:01crwdne2933313:0

Flores

crwdns2931217:0crwdne2931217:0

Kul 13, 2026

answered Kul 13, 2026 crwdns2933505:0crwdne2933505:0 Flores

Question 10

0 crwdns2873741:0crwdne2873741:0

Y is my rpm in keep going high n I lose pressure

crwdns2934197:0crwdne2934197:0 2000-2006 GMC Yukon crwdns2933315:00crwdne2933315:0

oldturkey03 857crwdns2936485:0crwdne2936485:0

crwdns2931741:0crwdne2931741:0

Kul 12, 2026

commented Kul 12, 2026 crwdns2933505:0crwdne2933505:0 oldturkey03

Question 11

0 crwdns2873741:0crwdne2873741:0

Why is my airbag light on?

crwdns2934197:0crwdne2934197:0 2006-2014 GMC Yukon crwdns2933315:00crwdne2933315:0

Mike J

crwdns2931731:0crwdne2931731:0

Sun 13, 2026

asked Sun 13, 2026 crwdns2933505:0crwdne2933505:0 Mike J

Question 12

0 crwdns2873741:0crwdne2873741:0

Power lift gate only partially opening

crwdns2934197:0crwdne2934197:0 2015-Present GMC Yukon crwdns2933315:00crwdne2933315:0

James

crwdns2931731:0crwdne2931731:0

N'w 29, 2025

asked N'w 29, 2025 crwdns2933505:0crwdne2933505:0 James

Question 13

1 crwdns2930801:0crwdne2930801:0

Why does my heated seats not work on the driver side?

2015-Present GMC Yukon crwdns2933313:01crwdne2933313:0

Anita

crwdns2931741:0crwdne2931741:0

N'w 29, 2025

commented N'w 29, 2025 crwdns2933505:0crwdne2933505:0 Anita

Question 14

1 crwdns2930801:0crwdne2930801:0

Replacing seals on the back hatch.

2000-2006 GMC Yukon crwdns2933313:01crwdne2933313:0

oldturkey03 857crwdns2936485:0crwdne2936485:0

crwdns2931217:0crwdne2931217:0

N'w 15, 2025

answered N'w 15, 2025 crwdns2933505:0crwdne2933505:0 oldturkey03

Question 15

0 crwdns2873741:0crwdne2873741:0

How to replace a 07-Yukon GM Ignition Switch Lock w/

crwdns2934197:0crwdne2934197:0 2006-2014 GMC Yukon crwdns2933315:00crwdne2933315:0

David Wilson

crwdns2931731:0crwdne2931731:0

N'w 2, 2025

asked N'w 2, 2025 crwdns2933505:0crwdne2933505:0 David Wilson

Question 16

1 crwdns2930801:0crwdne2930801:0

My truck doesnt crank but has power

2006-2014 GMC Yukon crwdns2933313:01crwdne2933313:0

jayeff 540,6crwdns2936485:0crwdne2936485:0

crwdns2931217:0crwdne2931217:0

Huk 15, 2025

answered Huk 15, 2025 crwdns2933505:0crwdne2933505:0 jayeff

Question 17

0 crwdns2873741:0crwdne2873741:0

I have a good actuator. How do I get my service 4wd off

crwdns2934197:0crwdne2934197:0 GMC Yukon crwdns2933315:00crwdne2933315:0

justin

crwdns2931731:0crwdne2931731:0

Mha 19, 2025

asked Mha 19, 2025 crwdns2933505:0crwdne2933505:0 justin

Question 18

0 crwdns2873741:0crwdne2873741:0

No start, but it cranks over.

crwdns2934197:0crwdne2934197:0 2000-2006 GMC Yukon crwdns2933315:00crwdne2933315:0

JuSt My LiFe

crwdns2931731:0crwdne2931731:0

Mud 14, 2025

asked Mud 14, 2025 crwdns2933505:0crwdne2933505:0 JuSt My LiFe

Question 19

1 crwdns2930801:0crwdne2930801:0

Why is my gas tank leaking above the tank? What could that be?

2006-2014 GMC Yukon crwdns2933313:01crwdne2933313:0

Jerry Wheeler 94,6crwdns2936485:0crwdne2936485:0

crwdns2931217:0crwdne2931217:0

Dzi 16, 2025

answered Dzi 16, 2025 crwdns2933505:0crwdne2933505:0 Jerry Wheeler

Question 20

1 crwdns2930801:0crwdne2930801:0

هل من الصحيح تغير زيت الفير

crwdns2934195:0crwdne2934195:0 2015-Present GMC Yukon crwdns2933313:01crwdne2933313:0

Ahmed

crwdns2942989:0crwdne2942989:0

Yan 20, 2025

answer accepted Yan 20, 2025 crwdns2933505:0crwdne2933505:0 Ahmed

crwdns2944620:0GMC Yukoncrwdne2944620:0

GMC Yukon crwdns2944634:0crwdne2944634:0