Error Code P1421 is defined as Cold Start Control. A problem which is detected when the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) wasn’t able to monitor the engine’s idle speed and ignition timing when the engine is started with pre-warming up condition.

This error code is a manufacturer-specific trouble code, meaning it does not apply to all vehicles makes. Rather, it applies only to specific vehicle makes, such as Nissan. Specification on the definition, troubleshooting, and repairs still vary from one make and model to another.


The PCM controls both the engine idle speed and ignition timing when the engine is started with a pre-warming up condition. This control promotes the activation of the three-way catalyst by heating the catalyst and reduces emissions.

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code in the vehicle’s system.

Possible Causes

Many factors contribute to this error code, some of the common causes are:

  • Lack of intake air volume (block air filter)
  • Fuel injection system (Clogged fuel injector or bad fuel pump)
  • Defective PCM
  • PCM that needs reprogramming

How to Check

Technicians start their diagnosis by using and OBD-II reader.

How to Fix

In most cases, Error Code P1421 can be fixed by just reprogramming the PCM (or for Nissan make ECM). Dealerships can offer to reprogram of this code, and the problem (along with the Check Engine light) can be fixed in no time.

The dealership will not charge you anything if the vehicle is still under warranty.

There is a factory service bulletin for the following Nissan models:

  • 2007-2009 Nissan Versa
  • 2007-2009 Nissan Versa Factory Service Bulletin OBDII Code P1421
  • 2009-2010 Nissan CUBE
  • 2009-2010 Nissan CUBE Factory Service Bulletin OBDII Code P1421

Check these service bulletins to get the best solution for your vehicle.