Video summary

How to clear code P0420 for good !!

Main summary

Key takeaways

Product Review

Product Reviewed

Seafoam (12 oz can) used to clear/check/fix a catalytic converter-related code P0420 without removing the catalytic converter—by spraying it through the oxygen sensor opening / exhaust inlet area.

Key Features / How It’s Used (from the video)

What comes with the can

  • A 12 oz Seafoam can
  • Includes:
    • a long straw
    • a small bendable hose/attachment (the straw can be repositioned for tight access)

Where it’s available

  • Purchased on Amazon (reviewer notes availability in physical stores is limited)

Amount used

  • Claims one can is enough, but most of it is used during the procedure

Procedure (Step-by-Step)

1) Remove the front oxygen sensor

  • Locate and remove the front oxygen sensor (near the exhaust manifold area)
  • Disconnect wiring first to avoid twisting the sensor wire during removal
  • Use a special oxygen sensor wrench/socket (a 38mm offset is mentioned) with a ratchet/extension for leverage

2) Insert the straw into the catalytic converter area

  • Insert the straw as far as possible into the opening leading to the top of the catalytic converter
  • The spray path is not directly into the engine (it’s aimed at the exhaust/catalyst area)

3) Spray Seafoam

  • Spray most/possibly nearly all of the can
  • Move/swirl the straw to coat the top of the catalytic converter

4) Soak time and restart

  • Wait about 20 minutes after spraying
  • On restart, expect heavy smoke at first
  • The smoke should dissipate after the exhaust heats up

5) Reinstall/maintenance steps

  • Clean reinstall the oxygen sensor
  • Apply anti-seize only on the threads (avoid the sensor tip)
  • Apply dielectric grease to the electrical connector
  • If an old clip snaps, zip tie the wiring harness to secure it

Pros (User Experience Claims)

Code outcome

  • P0420 cleared successfully (per the reviewer)
  • Check engine light (CEL) did not return during subsequent drives

Driving feel improvements

  • Smoother acceleration
  • Improved “pep” / responsiveness

Method advantage

  • Avoids removing the catalytic converter

Cost

  • Reported cost about $10
  • Also mentions a 2-pack for ~$20

Comparison vs dealer/fuel-additive methods

  • Reviewer says the CEL typically returned sooner when using fuel-system additives (gas tank additives)
  • After this exhaust/catalyst cleaning, the CEL stayed off longer (during their test period)

Cons / Cautions Mentioned

  • Straw positioning is the hardest part
    • The straw pops off if not kept secured properly while spraying
  • Mess/smoke is expected
    • The car will smoke heavily on startup until the exhaust heats and the Seafoam clears
  • Mechanical risk/note
    • The oxygen sensor wiring connector plastic may be old and can snap, requiring a zip tie workaround

Comparisons Made

  • Vs. fuel-tank additives
    • Reviewer: fuel additives often triggered the CEL to return sooner
    • This method: CEL stayed off longer for their test period
  • Addressing “putting Seafoam into the engine” concerns
    • Reviewer argues it goes into the exhaust past the engine (exhaust manifold/catalytic converter area), not into the cylinders

Numerical Results / Timelines

  • Wait time before starting: ~20 minutes
  • Smoke clearing: “a couple minutes,” then continues once exhaust gets hot
  • CEL validation:
    • 134 miles: CEL had not returned
    • 258 miles total: final test period
  • Final verdict: CEL still off, car “running great”

Overall “Unique Points” Highlighted

  • The long straw + bendable attachment enables access to the catalytic converter area
  • Amazon availability (limited in stores)
  • Reviewer notes one can is enough, but most is used
  • Applied through the oxygen sensor opening to reach catalytic converter top
  • Claim that it doesn’t harm the engine because it targets the exhaust side, not cylinder combustion
  • Requires oxygen sensor removal tools (special oxygen sensor socket/wrench)
  • Emphasizes disconnecting wiring first
  • Biggest practical difficulty: keeping straw positioned (it can pop off)
  • Expect temporary heavy smoke on restart; it should dissipate with heat
  • Reinstall guidance includes:
    • anti-seize on threads only
    • dielectric grease on connector
    • zip tie if clips break
  • Reported outcomes:
    • P0420 cleared
    • CEL stayed off for 258 miles
    • smoother acceleration
  • Cost/value: about $10 (or ~$20 for two cans)

Speakers

  • Single main speaker/reviewer (no clearly distinct multiple technical viewpoints shown)

Concise Verdict / Recommendation

Recommended (based on this video’s results): Using Seafoam (12 oz can with long straw) sprayed into the catalytic converter area via the oxygen sensor opening is reported to clear P0420 for the reviewer, with the check engine light staying off for 258 miles and improved acceleration.

Main downsides: difficulty keeping the straw positioned and temporary heavy smoke during restart.

Original video