P0421 — Warm Up Catalyst Efficiency Below Threshold (Bank 1)

Q: What does fault code P0421 mean?

P0421 means: Warm Up Catalyst Efficiency Below Threshold (Bank 1). It is a Powertrain (engine/transmission) fault code defined by the OBD-II standard.

Q: Can I keep driving with P0421?

With P0421 you can usually drive home and book an inspection within a few days unless the car feels abnormal.

Powertrain (engine/transmission)

Warm Up Catalyst Efficiency Below Threshold (Bank 1)

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Can I drive with P0421?

You can usually drive home and book an inspection within a few days.

Frequently asked questions

What does fault code P0421 mean?

P0421 means Warm Up Catalyst Efficiency Below Threshold (Bank 1).

Can I keep driving with P0421?

You can usually drive home and book an inspection within a few days.

Related fault codes

P0420 — Catalyst System Efficiency Below Threshold (Bank 1)
P0422 — Main Catalyst Efficiency Below Threshold (Bank 1)
P0423 — Heated Catalyst Efficiency Below Threshold (Bank 1)
P0424 — Heated Catalyst Temperature Below Threshold (Bank 1)
P0425 — Catalyst Temperature Sensor (Bank 1, Sensor 1)
P0426 — Catalyst Temperature Sensor Range/Performance (Bank 1, Sensor 1)
P0427 — Catalyst Temperature Sensor Low Input (Bank 1, Sensor 1)
P0428 — Catalyst Temperature Sensor High Input (Bank 1, Sensor 1)
P0429 — Catalyst Heater Circuit (Bank 1)

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