Secondary Air Check Valve
A one-way valve between the air pump and the exhaust, there to stop hot exhaust gas travelling back into the pump. It sits in exhaust heat and carbon and is the component that most often fails first in the whole secondary air system — when it seizes partly open it destroys the pump it was protecting, so a failed pump should always prompt a check of this valve before the new one is fitted.
Also known as: air injection check valve, one way valve, sai check valve, anti-backfire valve
Referenced by 21 codes
Codes involving this component (21)
- P2440 Secondary Air Injection System Switching Valve Stuck Open Bank 1 High
- P2442 Secondary Air Injection System Switching Valve Stuck Open Bank 2 High
- P0410 Secondary Air Injection System A Moderate
- P0411 Secondary Air Injection System A Incorrect Flow Detected Moderate
- P2257 Secondary Air Injection System Control A Circuit Low Moderate
- P2258 Secondary Air Injection System Control A Circuit High Moderate
- P2259 Secondary Air Injection System Control B Circuit Low Moderate
- P2430 Secondary Air Injection System Air Flow Pressure Sensor Circuit Bank 1 Moderate
- P2431 Secondary Air Injection System Air Flow Pressure Sensor Circuit Range/Performance Bank 1 Moderate
- P2432 Secondary Air Injection System Air Flow Pressure Sensor Circuit Low Bank 1 Moderate
- P2433 Secondary Air Injection System Air Flow Pressure Sensor Circuit High Bank 1 Moderate
- P2434 Secondary Air Injection System Air Flow/Pressure Sensor Circuit Intermittent/Erratic Bank 1 Moderate
- P2435 Secondary Air Injection System Air Flow Pressure Sensor Circuit Bank 2 Moderate
- P2436 Secondary Air Injection System Air Flow Pressure Sensor Circuit Range/Performance Bank 2 Moderate
- P2437 Secondary Air Injection System Air Flow Pressure Sensor Circuit Low Bank 2 Moderate
- P2438 Secondary Air Injection System Air Flow Pressure Sensor Circuit High Bank 2 Moderate
- P2439 Secondary Air Injection System Air Flow/Pressure Sensor Circuit Intermittent/Erratic Bank 2 Moderate
- P2445 Secondary Air Injection System Pump Stuck Off Bank 1 Moderate
- P2447 Secondary Air Injection System Pump Stuck Off Bank 2 Moderate
- P0491 Secondary Air Injection System Insufficient Flow — Bank 1 Low
- P0492 Secondary Air Injection System Insufficient Flow — Bank 2 Low
Other components in Exhaust and Emissions
- Oxygen Sensor 326
- EGR Valve 150
- Catalytic Converter 142
- NOx Sensor 118
- Reductant Injector 107
- Exhaust Gas Temperature Sensor 95
- Reductant Tank 95
- Diesel Particulate Filter 76
- SCR Catalyst 65
- EGR Cooler 62
- Exhaust Gas Differential Pressure Sensor 58
- Fuel Tank Pressure Sensor 58
- Exhaust Pressure Control Valve 56
- Reductant Heater 55
- Reductant Pump 51
- EVAP Vent Valve 43
- Exhaust Aftertreatment Fuel Injector 42
- Charcoal Canister 33
- EGR Position Sensor 32
- Secondary Air Injection Pump 32
- Reductant Temperature Sensor 29
- EVAP Leak Detection Pump 29
- EVAP Purge Valve 27
- Particulate Matter Sensor 24
- Reductant Control Module 24
- Reductant Level Sensor 23
- Secondary Air Switching Valve 22
- EGR Temperature Sensor 21
- Catalyst Heater 20
- Catalyst Temperature Sensor 20
- Fuel Filler Cap 18
- EGR Cooler Bypass Valve 16
- Reductant Quality Sensor 16
- Exhaust Back Pressure Sensor 15
- Purge Flow Sensor 13
- Direct Ozone Reduction Catalyst 13
- EGR Vacuum Solenoid 9
- Fuel Vapour Temperature Sensor 5
- Fuel Additive Control Module 4
- Fuel Additive Tank 4
Information, not instruction
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