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 P0411 : Secondary Air Injection (AIR) System Incorrect Air Flow Detected

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
AIR Pump Relay Coil Voltage Supply | P0418 | P0418 | P0418 | P0411
AIR Pump Relay Switch Voltage Supply | P0411 | P0411 | -- | P0411
AIR Pump Voltage Supply | P0411 | P0411 | -- | --
AIR Pump Relay Control | P0418 | P0418 | P0418 | P0411
AIR Pump Ground | -- | P0411 | -- | P0411

### Typical Scan Tool Data

#### AIR Pressure Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Parameter Normal Range: BARO to 240 kPa Operating Conditions: Engine running under various operating conditions
5-Volt Reference | 20-80 kPa | 30-80 kPa | 20-80 kPa
AIR Pressure Sensor Signal | 0 kPa | 276 kPa | 276 kPa
Low Reference | -- | 276 kPa | --

### Circuit/System Description

The secondary air injection (AIR) system aids in the reduction of hydrocarbon emissions during a cold start. The electric air pump forces fresh air into the exhaust stream in order to accelerate the catalyst operation. An AIR system pressure sensor is used to monitor the air flow from the AIR pump. The engine control module (ECM) supplies 5 volts to the 5 V reference circuit and supplies a ground to the low reference circuit. The sensor provides a signal voltage to the ECM relative to the pressure changes within the AIR system.

Ignition voltage is supplied directly to the secondary air injection pump relay. The engine control module (ECM) controls the relay by grounding the control circuit , which will switch the AIR pump relay. With the relay contacts closed, battery voltage is supplied to the AIR pump.

### Conditions for Running the DTC

• | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0418, P0420, P0606, P0641, P0651, P2430, P2431, P2432, P2433, P2440, P2444 are not set.

• | More than 60 minutes has elapsed since the last cold start.

• | The system voltage is 9-18 volts.

• | The BARO parameter is more than 70 kPa.

• | The MAF sensor parameter is less than 33 g/s.

• | The AIR system is commanded ON.

• | The conditions are stable for more than 5 seconds.

• | DTC P0411 runs once per trip start up when the above conditions are met and AIR pump operation is requested.

### Conditions for Setting the DTC

• | The difference between the predicted system pressure and the actual system pressure is more than 6 kPa.

• | DTC P0411 sets within 22 seconds when the above condition is met.

### Action Taken When the DTC Sets

DTC P0411 is a Type B DTC.

### Conditions for Clearing the MIL/DTC

DTC P0411 is a Type B DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Secondary Air Injection System Description

#### 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. Verify that DTCs P0418, P2431, P2432, P2433, P2444, or P2445 are not set.

⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Ignition ON, command the Secondary Air Injection Pump Relay ON and OFF with a scan tool. The air pump should turn ON and OFF.
3. Engine running, command the Secondary Air Injection Pump Relay ON with a scan tool while observing the Secondary Air Injection Pressure Sensor parameter. The reading should change greater than 10 kPa.
4. 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.

### Circuit/System Testing

1. Inspect the AIR system for the following conditions:

• | Hoses/pipes for a restriction or blockage

• | Hoses/pipes for being disconnected

• | Plugged pressure sensor port

⇒ | If a condition is located, repair as necessary.

⇒ | If a condition is not located, and the AIR pump operates with no pressure change, replace the G21 AIR pump.

2. Ignition OFF, disconnect the KR25 secondary air injection pump relay.
3. Ignition ON, verify that a test lamp does not illuminate between the controlled output circuit terminal 87 and ground.

⇒ | If the test lamp illuminates, test the controlled output circuit for a short to voltage.

4. Verify that a test lamp illuminates between the secondary air injection pump relay switch B+ circuit terminal 30 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the relay coil ignition circuit fuse is open, test all components connected to the ignition circuit and replace as necessary.

5. Ignition OFF, disconnect the harness connector at the G21 AIR pump.
6. Test for less than 2 Ω between the AIR pump ground circuit terminal 1 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

7. Connect the harness connector at the G21 AIR pump.
8. Connect the J 36169-HD Heavy Duty Fused Jumper with a 50 A fuse between the AIR pump relay switch B+ circuit terminal 30 and the controlled output circuit terminal 87. The AIR pump should turn ON.

⇒ | If the AIR pump does not activate, test the controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the G21 AIR pump.

9. If all circuits test normal, replace the KR25 secondary air injection pump relay.

### Component Testing

#### Relay Test

1. Ignition OFF, disconnect the KR25 secondary air injection pump relay.
2. Test for 70-110 Ω between terminals 85 and 86.

⇒ | If the resistance is not within the specified range, replace the KR25 secondary air injection pump relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If not the specified value, replace the KR25 secondary air injection pump relay.

4. Install a 20 A fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒ | If greater than the specified range, replace the KR25 secondary air injection pump relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Secondary Air Injection Pump Replacement