P1421 Honda Cold Start Control

Possible causes

– Lack of intake air volume (block air filter)
– Fuel injection system (Clogged fuel injector or bad fuel pump)
– Faulty Engine Control Module (ECM)

What about the obd code?

The P1421 Honda code is detected when The Engine Control Module (ECM) does not control ignition timing and engine idle speed properly when engine is started with pre-warming up condition.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P1421 Honda Description

The Engine Control Module (ECM) controls ignition timing and engine idle speed when engine is started with pre-warming up condition. This control promotes the activation of three way catalyst by heating the catalyst and reduces emissions.