For 1990-2009 cars

### 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 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

• | The engine is running, and a cold start has been detected

• | Vehicle speed less than 2 km/h

• | Throttle position sensor less than 2 percent

• | Airflow per cylinder 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, P0300, P0335, P0336, P0351, P0352, P0353, P0354, 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 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. 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.

### Circuit/System Testing

• | Inspect the air intake system for the following:

- | 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 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--Refer to Symptoms - Engine Exhaust .

• | Inspect the engine mechanical for items that could alter the air flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .