GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P1400

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provide 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 run time
    • Park/Neutral position
    • Vehicle speed

The actual model is then compared to the expected exhaust energy model.

Conditions for Running the DTC
    • The engine is running, and a cold start has been detected.
    • The vehicle speed is less than 2 km/h (1 mph).
    • The throttle position sensor is less than 2 percent.
    • The airflow per cylinder is greater than 40 mg.
    • DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0201-P0208, P0300, P0301-P0308, P0335, P0336, P0351-P0358, P0506, P0507, P0601, P0602, P0604, P0606, P0607, P060D, P062F, P0641, P0651, P1516, P1682, P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, P2176, or P2610 are not set.

Conditions for Setting the DTC
    • The average accumulated exhaust energy model is not within a calibrated range to the estimated average exhaust energy model. The average accumulated exhaust energy is less than -11 kj/s or greater than 0.25 kj/s of the estimated average accumulated exhaust energy.
    • This DTC runs within 10 seconds of start-up. This diagnostic runs once per trip when a cold start has been determined.

Action Taken When the DTC Sets

DTC P1400 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P1400 is a Type A DTC.

Diagnostic Aids

Any loading of the engine that lowers engine RPM, such as partial application of the clutch, A/C cycling, etc. during the first 120 seconds of the engine run time may set this DTC.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Allow the engine to cool.
  2. Start and idle the engine for at least 2 minutes.
  3. DTC P1400 should run and pass.
  4. Engine running, observe the DTC information with a scan tool. DTC P1400 should not set.
  5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
    • Inspect the air intake system for the following:
       - Damage, restriction, or modification
       - Dirty or deteriorating air filter element
       - Crankcase ventilation system for correct operation.
       - Water intrusion
       - Vacuum leak and other unmetered air downstream of the MAF sensor
       - Intake manifold leak
    • Inspect the exhaust system for the following:
       - Water intrusion
       - Exhaust leak
       - Damaged, restricted, modified or enhanced exhaust system.
    • Inspect the engine mechanical for items that could alter the air flow into the combustion chamber.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.