Buick Regal: 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 catalyst must be warmed to efficiently reduce the emissions. The cold start strategy is to reduce the amount of time it takes to warm the catalyst. During a cold start, the engine spark timing is altered to allow the catalyst to warm quickly. This diagnostic monitors the following to build an exhaust energy model:

• Spark advance
• Engine airflow
• Engine coolant temperature
• Engine run time

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, P0114, P0116, P0117, P0118, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0222, P0223, P0300, P0301, P0302, P0303, P0304, P0335, P0336, P0351, P0352, P0353, P0354, P0641, P0651, P0697, P06A3, P2122, P2123, P2127, P2128, P2135, and P2138 are not set.
• The engine coolant temperature (ECT) is between -12 to +56ºC (10 - 132ºF).
• The calculated 3-way catalyst temperature is colder than 500ºC (932ºF).
• The barometric (BARO) pressure is greater than 75 kPa.
• The engine control module (ECM) will exit the diagnostic if the calculated 3-way catalyst temperature is greater than 1, 000ºC (1832ºF) when the engine run time is greater than 17 s.
• Vehicle speed is less than 1.6 km/h (1 mph).
• The accelerator pedal is not depressed.
• The ECM will exit the diagnostic if the engine run time is greater than a calibrated value.
• This DTC runs within the first 15 s 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

DTC P1400 is a Type A DTC.

Conditions for Clearing the DTC

DTC P1400 is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Wiring Schematics (LTG)

Connector End View Reference

Component Connector End View Index

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle OFF, allow the engine to cool to be within the temperatures listed in the Conditions for Running the DTC.

2. Engine running.

3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset.

You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

4. Verify the DTC does not set.

• If the DTC sets

1. Verify that none of the conditions listed below exists with the air intake system:
   • 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 mass air flow (MAF) sensor
   • Intake manifold leak
   • If any of the conditions exist

     Repair as necessary.

   • Go to next step: If none of the conditions exist
2. Verify that none of the conditions listed below exists with the exhaust system:
   • Exhaust leak
   • Damaged, restricted, or modified exhaust system - Refer to Symptoms - Engine Exhaust.
   • If any of the above conditions exist

     Repair as necessary.

   • Go to next step: If none of the conditions exist
3. If all of the above conditions test normal, inspect for an engine mechanical condition that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine Mechanical.

• Go to next step: If the DTC does not set

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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