- Jan 3, 2015
- 75
2008 Trailblazer, 4.2, 109,000
Last three cold start ups there has been a roar from the engine compartment for a short time before it goes away; my initial thought was fan clutch and its something I can fix as I replaced my water pump this summer. However, when listening to the sound with my hood up, it sounded closer to the throttle bottle or firewall rather than from the fan clutch. (youtube video)
This has happened the last three cold starts and lasts 5-10 seconds. Has not occurred during warm starts.
Trouble codes are P2440 (secondary air injection system shut-off valve stuck open). P0411 (secondary air injection system shutoff valve stuck open).
I checked fuses 54, 55 and 56 all related to the secondary air system and all fuses were not blown. I looked at the live data on my non bi-directional scanner and nothing looked off (youtube video)
Is the likely fix to replace the secondary air injection check valve (Rockauto $125)? Something else? Is there troubleshooting I should/can do? Is the vehicle okay for short trips, longer trips until I get the parts? <<<<edited to add a comment from Roadie years ago about the SAIS: If you can get one cheaper on-line, no need to rush to install one unless you're in a hurry to pass an emissions test. The SAIS function is only to hasten the engine's entry into closed loop mode on a cold start-up. It's an EPA mandate that reduces emissions, but it has guaranteed zero effect on driving once it's warmed up a couple of minutes.>>>
I checked fuses 54, 55 and 56 all related to the secondary air system and all fuses were not blown. Hoses all appear to be good, wire connectors all appear good. I looked everywhere but especially focused on the secondary air injection valve.
Last three cold start ups there has been a roar from the engine compartment for a short time before it goes away; my initial thought was fan clutch and its something I can fix as I replaced my water pump this summer. However, when listening to the sound with my hood up, it sounded closer to the throttle bottle or firewall rather than from the fan clutch. (youtube video)
This has happened the last three cold starts and lasts 5-10 seconds. Has not occurred during warm starts.
Trouble codes are P2440 (secondary air injection system shut-off valve stuck open). P0411 (secondary air injection system shutoff valve stuck open).
I checked fuses 54, 55 and 56 all related to the secondary air system and all fuses were not blown. I looked at the live data on my non bi-directional scanner and nothing looked off (youtube video)
Is the likely fix to replace the secondary air injection check valve (Rockauto $125)? Something else? Is there troubleshooting I should/can do? Is the vehicle okay for short trips, longer trips until I get the parts? <<<<edited to add a comment from Roadie years ago about the SAIS: If you can get one cheaper on-line, no need to rush to install one unless you're in a hurry to pass an emissions test. The SAIS function is only to hasten the engine's entry into closed loop mode on a cold start-up. It's an EPA mandate that reduces emissions, but it has guaranteed zero effect on driving once it's warmed up a couple of minutes.>>>
I checked fuses 54, 55 and 56 all related to the secondary air system and all fuses were not blown. Hoses all appear to be good, wire connectors all appear good. I looked everywhere but especially focused on the secondary air injection valve.