DTC Code P1421 – What does this code mean?

<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The illumination of the engine light indicates a detected issue with the cold start control system. This could be due to a malfunctioning cold start injector, a faulty coolant temperature sensor, or issues with the engine control module (ECM).</li> <li><b>Rough Idle During Cold Start</b>: A rough idle when starting the engine cold can be a symptom of a problem with the cold start control system. Potential causes include a defective cold start valve, incorrect air-fuel mixture, or a malfunctioning idle air control valve.</li> <li><b>Increased Fuel Consumption</b>: Higher fuel consumption during cold starts may indicate an issue with the cold start control system. This could be due to a faulty cold start injector or an incorrect signal from the coolant temperature sensor.</li> <li><b>Difficulty Starting Engine in Cold Weather</b>: Difficulty starting the engine in cold weather can be a symptom of a malfunctioning cold start control system. Potential causes include a defective cold start injector, a faulty coolant temperature sensor, or issues with the ECM.</li> </ul>

<ul><li>Insufficient intake air volume due to a blocked air filter, which restricts airflow and affects engine performance.</li><li>Issues in the fuel injection system, such as clogged fuel injectors or a malfunctioning fuel pump, leading to improper fuel delivery.</li><li>A faulty Engine Control Module (ECM) that fails to manage the cold start process effectively.</li></ul>

<ul> <li><b>Initial Scan</b>: Use an OBD-II scanner to confirm the presence of DTC P1421 and check for any additional codes that may be related.</li> <li><b>Inspect Coolant Temperature Sensor</b>: Check the coolant temperature sensor for proper operation. Ensure the sensor is providing accurate temperature readings.</li> <li><b>Check Cold Start Injector</b>: Inspect the cold start injector for proper function. Ensure it is not clogged and is receiving the correct voltage.</li> <li><b>Examine Wiring and Connectors</b>: Inspect the wiring and connectors related to the cold start system for any signs of damage, corrosion, or loose connections.</li> <li><b>Test Engine Control Module (ECM)</b>: Verify that the ECM is functioning correctly and is properly controlling the cold start system.</li> <li><b>Perform a Cold Start Test</b>: Conduct a cold start test to observe the engine's behavior and ensure the cold start system is operating as intended.</li> <li><b>Review Technical Service Bulletins (TSBs)</b>: Check for any TSBs related to the cold start system for the specific vehicle model, as they may provide additional diagnostic procedures or solutions.</li></ul>

<p>The DTC code P1421 indicates an issue with the Cold Start Control system. This can lead to poor engine performance during cold starts, increased emissions, and potential long-term engine damage.</p><ul><li><b>Immediate Actions:</b> Inspect the cold start injector, temperature sensors, and related wiring.</li><li><b>Potential Risks:</b> Delayed repair can result in harder starts, rough idling, and increased fuel consumption.</li></ul>