Uploaded September 2026 | Updated September 2026, 1 hour ago
Got a P0420 catalytic converter code? Don’t rush to replace the catalytic converter yet. In this video, I explain what P0420 really means, how the engine computer compares the upstream and downstream oxygen sensors, and what you should check first before spending money on an expensive repair. You’ll learn how exhaust leaks, bad oxygen sensor readings, fuel trim problems, misfires, oil burning, coolant burning, and cheap aftermarket converters can all trigger a P0420 code.
I’ll also show the smart diagnostic order: scan for all codes, check engine running condition, inspect for exhaust leaks, look at oxygen sensor live data, review fuel trims, and only then decide whether the catalytic converter is actually bad.
Tools to Get the Job Done:
amzn.to/3RXKM27 - All-In-One OBD2 Scanner
amzn.to/3PY2Mcl - Digital Multimeter Tester
amzn.to/4oGFWCO - Smoke Machine
amzn.to/43G7HBN - Portable Cordless Magnetic Trouble Light
amzn.to/4elM5kp - Digital Multimeter
amzn.to/4enFnsD - Torque Wrench
amzn.to/4gtGo58 - Infrared Thermometer
Timecode:
00:00:00 - Short intro
00:01:02 - What P0420 actually means.
00:01:53 - First check: are there other codes?
00:02:43 - Check for exhaust leaks before the sensors.
00:03:30 - Check oxygen sensor behavior.
00:04:22 - Check fuel trims and engine running condition.
00:05:12 - Check for misfires, oil burning, and coolant burning.
00:06:00 - Check for cheap or wrong catalytic converter replacement.
00:06:39 - Don’t forget temperature testing.
00:07:15 - Tools that help diagnose P0420.
00:08:08 - What to check first, in the correct order.
00:08:46 - Can you keep driving with P0420?
Affiliate Disclosure: Some links in this description are Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you. Thanks for supporting the channel!
Got a P0420 catalytic converter code? Don’t rush to replace the catalytic converter yet. In this video, I explain what P0420 really means, how the engine computer compares the upstream and downstream oxygen sensors, and what you should check first before spending money on an expensive repair. You’ll learn how exhaust leaks, bad oxygen sensor readings, fuel trim problems, misfires, oil burning, coolant burning, and cheap aftermarket converters can all trigger a P0420 code.
I’ll also show the smart diagnostic order: scan for all codes, check engine running condition, inspect for exhaust leaks, look at oxygen sensor live data, review fuel trims, and only then decide whether the catalytic converter is actually bad.
Tools to Get the Job Done:
amzn.to/3RXKM27 - All-In-One OBD2 Scanner
amzn.to/3PY2Mcl - Digital Multimeter Tester
amzn.to/4oGFWCO - Smoke Machine
amzn.to/43G7HBN - Portable Cordless Magnetic Trouble Light
amzn.to/4elM5kp - Digital Multimeter
amzn.to/4enFnsD - Torque Wrench
amzn.to/4gtGo58 - Infrared Thermometer
Timecode:
00:00:00 - Short intro
00:01:02 - What P0420 actually means.
00:01:53 - First check: are there other codes?
00:02:43 - Check for exhaust leaks before the sensors.
00:03:30 - Check oxygen sensor behavior.
00:04:22 - Check fuel trims and engine running condition.
00:05:12 - Check for misfires, oil burning, and coolant burning.
00:06:00 - Check for cheap or wrong catalytic converter replacement.
00:06:39 - Don’t forget temperature testing.
00:07:15 - Tools that help diagnose P0420.
00:08:08 - What to check first, in the correct order.
00:08:46 - Can you keep driving with P0420?
Affiliate Disclosure: Some links in this description are Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you. Thanks for supporting the channel!
