Received code P1400 engine light on what would cause this code?
GMC Truck Envoy - 2WD ' Envoy, Rainier, TrailBlazer, Ascender (VIN S/T) Service Manual ' Document ID: 1655997
• 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 provides an overview of each diagnostic category.
DTC P1400: Cold Start Emission Reduction Control System
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
• A cold start has been detected.
• The vehicle speed is less than 2 km/h.
• The engine is at idle with no input from the accelerator pedal.
• The airflow per cylinder is greater than 80 mg/cylinder.
• DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113,
P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0220, P0222, P0223,
P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0335, P0336, P0351,
P0352, P0353, P0354, P0355, P0356, P0502, P0506, P0507, P0601, P0602,
P0603, P0604, P0606, P0607, P062F, P0641, P0651, P1101, P1516, P1682,
P2101, P2119, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138,
P2176, P2610 are not set.
• This DTC runs for 15 seconds within the first 70 seconds of start
up. This diagnostic runs once per trip when a cold start has been
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
• 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.
Any loading of the engine that lowers engine RPM, such as with partial
application of the clutch, during the first 70 seconds of engine run
time may set this DTC.
Allow the engine to cool. Monitor the Cold Startup parameter. This
should indicate Yes. Start and idle the engine for at least 2 minutes.
DTC P1400 should run and pass.
• Inspect the air intake system for the following:
- If any other DTCs are set, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle.
- Modified, damaged, or restricted
- Dirty or deteriorating air filter element
- Crankcase ventilation system for correct operation--Refer to Crankcase Ventilation System Inspection/Description.
- 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 - Engine Exhaust .
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Jun 30, 2011 |
2006 Chevrolet Trailblazer Ext