Error Code P1400 is defined as Cold Start Emission Reduction Control System.

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 BMW, Chevrolet, Ford, Mitsubishi, and Nissan. Specification on the definition, troubleshooting, and repairs still vary from one make and model to another.


For the catalytic converter to efficiently reduce emissions, it should be properly warmed. Cold starting strategy reduces the amount of time it takes to heat the catalytic converter. During cold start, the idle speed of the engine is increased, while the spark timing is retarded. This process allows the catalytic converter to warm up faster. This diagnostic process monitors the following to build an exhaust energy model:

  • Engine speed
  • Engine coolant temperature
  • Engine airflow
  • Engine runtime
  • Spark advance
  • Throttle position
  • Vehicle speed
  • Park/neutral position

Common Symptoms

As with other error codes, this trouble code activates the Check Engine light and registers the code to the system.

Possible Causes

Many factors lead to this error code. Some of the most common causes are:

  • Defective air intake system
  • Defective or dirty air filter element
  • Vacuum leak
  • Water intrusion exhaust system

How to Check

Start your diagnosis for this error code by checking the air intake system. Look for signs of damage, modifications or restrictions, and water intrusion.

Check the air filter element for dirt or signs of deterioration.

Check the crankcase ventilation system for proper operation. You can refer to the Crankase Ventilation System Inspection/Diagnosis.

Check for a vacuum leak and un-metered air downstream of the MAF (mass airflow) sensor.

Then inspect the exhaust system for an exhaust leak and signs of water intrusion.

Next, check the engine mechanical for items that could change the airflow into the combustion chamber.

How to Fix

Repairs for this code are as easy as the diagnosis above. That means the problem should be properly diagnosed before one can start any repair procedures. Common repairs for this error code are:

  • Repair damage or replace the air intake system
  • Clean the throttle bore
  • Clean the MAF (mass airflow) sensor elements

In most cases, cleaning the throttle body, MAF sensor and putting a new air filter usually solves this error code.