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DTC P1400

DIAGNOSTIC INSTRUCTIONS


Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Testing and Inspection\Initial Inspection and Diagnostic Overview\Diagnostic System Check - Vehicle
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC DESCRIPTOR

DTC P1400
Cold Start Emission Reduction Control System

CIRCUIT/SYSTEM DESCRIPTION
The catalytic converter must be warmed to efficiently reduce the emissions. The cold start strategy is to reduce the amount of time it takes to warm the catalytic converter. During a cold start, the engine idle speed is elevated and spark timing is retarded to allow the catalyst to warm quickly. This diagnostic monitors the following to build an exhaust energy model:


Engine speed
Spark advance
Throttle position
Engine airflow
Engine coolant temperature
Engine runtime
Park/neutral position
Vehicle speed
The actual model is then compared to the expected exhaust energy model.

CONDITIONS FOR RUNNING THE DTC


DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0128, P0200, P0220, P0300, P0335, P0336, P0351, P0352, P0353, P0354, P0355, P0356, P0357, P0358, P0502, P0503, P0506, P0507, P0601, P0602, P0604, P0606, P0641, P0651 are not set.
The engine is at idle with no input from the accelerator pedal.
A cold start has been detected.
The vehicle speed less than 3 km/h (2 mph) .
Airflow per cylinder greater than 80 mg/cylinder
This DTC runs for 15 seconds within the first 2 minutes of start up. This diagnostic runs once per trip when a cold start has been determined.
CONDITIONS FOR SETTING THE DTC
The actual exhaust energy model does not match the expected exhaust energy model.

ACTION TAKEN WHEN THE DTC SETS


The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
CONDITIONS FOR CLEARING THE MIL/DTC


The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
DIAGNOSTIC AIDS
Any loading of the engine that lowers engine RPM, such as with partial application of the clutch, during the first 120 seconds of engine runtime may set this DTC.

CIRCUIT/SYSTEM VERIFICATION
Allow the engine to cool. Start and idle the engine for at least 2 minutes . DTC P1400 should run and pass.

CIRCUIT/SYSTEM TESTING


Inspect the air intake system for the following:
Damage, restriction, or improper modification
Dirty or deteriorating air filter element
Crankcase ventilation system for correct operation-Refer to Crankcase Ventilation System Inspection/Diagnosis.
Water intrusion
Vacuum leak and other un-metered air downstream of the mass air flow (MAF) sensor
Intake manifold leak
Inspect the exhaust system for the following:
Water intrusion
Exhaust leak
Damaged, restricted, modified or enhanced exhaust system-Refer to Symptoms - Exhaust System. See: Engine, Cooling and Exhaust\Exhaust System\Testing and Inspection\Symptom Related Diagnostic Procedures\Symptoms - Engine Exhaust
Inspect the engine mechanical for items that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine. See: Engine, Cooling and Exhaust\Engine\Testing and Inspection\Symptom Related Diagnostic Procedures\Symptoms - Engine Mechanical