Warm Up Catalyst Efficiency Below Threshold (Bank 1)
| Code | P0421 |
| Description | Warm Up Catalyst Efficiency Below Threshold (Bank 1) |
| Possible Causes | The warm-up catalytic converter is not performing efficiently. |
| System | Emission Controls |
Warm Up Catalyst Efficiency Below Threshold (Bank 1). This diagnostic trouble code (DTC) is stored when the vehicle's onboard computer detects an issue with the emission controls.
P = Powertrain code
0 = Generic (SAE standard)