Chapa Lab · MotorAUTOCODES
계정 불필요 무료 조회 VIN은 요청 시에만

부품을 바꾸기 전에 경고를 이해하세요

자동차는 코드로 말합니다.
여기서 뜻을 확인하세요.

OBD-II 코드와 계기판 경고등, 가능한 원인, 안전한 확인 방법과 운전을 멈춰야 할 때를 이해하세요. VIN과 공식 리콜은 요청할 때만 조회합니다.

OBD-II / LIVEA clear clue before replacing a part
경고 해석하기 정비소 진단을 대신하지 않습니다. 먼저 이해하고 판단하도록 돕습니다.

AUTO / DIAG 01

무엇을 확인할까요?

Try:
P0420

Guidance, not diagnosis

Catalyst system efficiency below threshold

Priority medium

The control module compares signals before and after the catalyst and sees less exhaust cleaning than expected. This code alone does not prove the catalyst must be replaced.

Possible causes

  1. 01Exhaust leak
  2. 02Aged or unstable oxygen sensor
  3. 03Degraded catalyst
  4. 04Incorrect mixture or combustion

Safe checks

  • Check related mixture or misfire codes.
  • Inspect for leaks only when the exhaust is cold.
  • Compare sensor data before replacing parts.

A code is a clue; it does not prove that one particular part has failed.

STEP 01

Read the warning

Enter the reader code, dashboard light or vehicle data.

STEP 02

Understand the scope

Separate meaning, possible causes and safety signals without false certainty.

STEP 03

Decide with context

Save or print a clear sheet before speaking with a workshop or replacing parts.

For people, not control modules

More context before opening the toolbox.

Buying a used car?

Check the VIN and review general safety campaigns before deciding.

Did a warning light appear?

Tell a routine service need from a signal that requires a safe stop.

Speaking with a workshop?

Bring a printable sheet with the code, symptoms and useful questions.

Clean-workshop privacy

No account. No vehicle history. No stored VIN.

Local explanations run in your browser. VIN and recall requests go to NHTSA only when you ask. Advertising is prepared for the future but remains disabled in this draft.

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