Check engine code P0492?
#1
Check engine code P0492?
I keep getting this check engine code about once a week. I've checked all the lists of codes I can find online and it's never listed. Any idea what this is, it always happens 10-12 minutes into my drive and only in the morning
#2
Tech Contributor
**edit** looks like 2004 only...
Last edited by lucky131969; 07-08-2009 at 10:20 AM.
#3
Tech Contributor
DTC P0491 or P0492
Circuit Description
The secondary air injection (AIR) pump system is designed to lower exhaust emission levels on a start up. The AIR pump is timed to remain ON for approximately 1 minute or until Closed Loop is achieved.
The powertrain control module (PCM) commands the AIR pump relay ON by supplying a ground to the AIR pump relay control circuit. This action energizes the AIR pump, forcing fresh air into the exhaust stream. The PCM also commands the AIR solenoid ON which applies engine vacuum to the AIR shut-off valve. With vacuum applied to the AIR shut-off valve, airflow from the AIR pump flows through the pipes/hoses to the exhaust check valves, then enters into the exhaust stream. The air, oxygen, that is introduced into the exhaust system accelerates catalyst operation. When inactive, the check exhaust valves and the shut-off valve prevent air flow in either direction.
The PCM detects a system air flow condition by monitoring the heated oxygen sensors (HO2S) and Short Term Fuel Trim during normal Open Loop AIR system operation. This is a passive test. If the passive test indicates a pass, the PCM takes no further action. If the passive test fails or is inconclusive, the diagnostic will proceed with an intrusive or active test. The PCM will command the AIR system ON during Closed Loop operation under normal operating conditions. The active test will pass or fail based on the response from the HO2S. A lean HO2S response indicates that the AIR system is functioning normally. An increasing Short Term Fuel Trim value also indicates a normal functioning system. The AIR diagnostic consists of the passive test and the active tests. The AIR diagnostic requires failure of the passive and active tests on 2 consecutive key cycles to illuminate the malfunction indicator lamp (MIL) and stores a DTC. If the PCM detects that the HO2S and Short Term Fuel Trim did not respond as expected on one of the engine banks, DTC P0491 for bank 1 or DTC P0492 for bank 2 sets.
Circuit Description
The secondary air injection (AIR) pump system is designed to lower exhaust emission levels on a start up. The AIR pump is timed to remain ON for approximately 1 minute or until Closed Loop is achieved.
The powertrain control module (PCM) commands the AIR pump relay ON by supplying a ground to the AIR pump relay control circuit. This action energizes the AIR pump, forcing fresh air into the exhaust stream. The PCM also commands the AIR solenoid ON which applies engine vacuum to the AIR shut-off valve. With vacuum applied to the AIR shut-off valve, airflow from the AIR pump flows through the pipes/hoses to the exhaust check valves, then enters into the exhaust stream. The air, oxygen, that is introduced into the exhaust system accelerates catalyst operation. When inactive, the check exhaust valves and the shut-off valve prevent air flow in either direction.
The PCM detects a system air flow condition by monitoring the heated oxygen sensors (HO2S) and Short Term Fuel Trim during normal Open Loop AIR system operation. This is a passive test. If the passive test indicates a pass, the PCM takes no further action. If the passive test fails or is inconclusive, the diagnostic will proceed with an intrusive or active test. The PCM will command the AIR system ON during Closed Loop operation under normal operating conditions. The active test will pass or fail based on the response from the HO2S. A lean HO2S response indicates that the AIR system is functioning normally. An increasing Short Term Fuel Trim value also indicates a normal functioning system. The AIR diagnostic consists of the passive test and the active tests. The AIR diagnostic requires failure of the passive and active tests on 2 consecutive key cycles to illuminate the malfunction indicator lamp (MIL) and stores a DTC. If the PCM detects that the HO2S and Short Term Fuel Trim did not respond as expected on one of the engine banks, DTC P0491 for bank 1 or DTC P0492 for bank 2 sets.
#5
3rd Gear
Member Since: May 2004
Location: Gainesville VA
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#6
Instructor
There was a thread on here several months ago, complete with pictures. The gist of what I recall is removing a couple of hoses and cleaning with some carb cleaner.
I have the same code - hoping to find the info again.
I have the same code - hoping to find the info again.
#7
Safety Car
#9
po492
This forum is awesome. A little carb cleaner , w d 40 and air and its's a go. I don't know how anybody owns a vette with out getting help from this website (other than give GM dealers the farm). My experience with owning 2 vette is that they are about like helicopters, work on them for 8 hrs for every hour you drive them
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Rotortrash (04-08-2023)
#10
Racer
P0492 failure
I TO HAVE THIS FAILURE. I PURCHASED AUTO ENGINUITY SO I COULD GET A BETTER UNDERSTANDING OF WHAT MIGHT BE GOING ON. SO FAR I OBSERVED THE PASSANGER BANK 02 SENSOR DOES NOT READ ANY OXYGEN DURING STARTUP WHERE THE DRIVERS SIDE DID. KNOWING THE DRIVER SIDE IS OK ELIMINATES THE AIR PUMP. SO TRYING TO CHECK THE SECONDARY CHECK VALVE MIGHT BE EASER THAN JUST REPLACEING 02 SENSOR. I WAS ABLE TO REMOVE THE HOSE BEHIND THE ENGINE BLOCK. YES TIGHT. TRIED TO REMOVE IT BUT IT WAS ON WAY TO TIGHT. BEEN ON FOR 10 YRS. SPRAYED OIL BUT I KNOW THATS NOT THE SOLUTION. THE DRIVERS SIDE WAS LEAKING JUST A LITTLE. GOOD TIME TO REPLACE BOTH. DISCONNECTED PASSENGER EXHAUST TUBE AND WAS ABLE TO MAKE A HOSE TO FIT ON THE END OF THE VALVE. BARELY WAS ABLE TO GET ANY AIR FLOW THROUGH IT. SO THIS CONFIRMED THE LOW AIR FAILURE FOR ME. ITS ONLY THE INTAKE REMOVAL TO DO SO THATS WHERE ILL BE GOING. I HOPE THIS SHEADS MORE LIGHT ON THE SUBJECT FOR U
#11
Instructor
Kept getting 0492 Check Engine Code , Passenger side AIR check valve stuck
I TO HAVE THIS FAILURE. I PURCHASED AUTO ENGINUITY SO I COULD GET A BETTER UNDERSTANDING OF WHAT MIGHT BE GOING ON. SO FAR I OBSERVED THE PASSANGER BANK 02 SENSOR DOES NOT READ ANY OXYGEN DURING STARTUP WHERE THE DRIVERS SIDE DID. KNOWING THE DRIVER SIDE IS OK ELIMINATES THE AIR PUMP. SO TRYING TO CHECK THE SECONDARY CHECK VALVE MIGHT BE EASER THAN JUST REPLACEING 02 SENSOR. I WAS ABLE TO REMOVE THE HOSE BEHIND THE ENGINE BLOCK. YES TIGHT. TRIED TO REMOVE IT BUT IT WAS ON WAY TO TIGHT. BEEN ON FOR 10 YRS. SPRAYED OIL BUT I KNOW THATS NOT THE SOLUTION. THE DRIVERS SIDE WAS LEAKING JUST A LITTLE. GOOD TIME TO REPLACE BOTH. DISCONNECTED PASSENGER EXHAUST TUBE AND WAS ABLE TO MAKE A HOSE TO FIT ON THE END OF THE VALVE. BARELY WAS ABLE TO GET ANY AIR FLOW THROUGH IT. SO THIS CONFIRMED THE LOW AIR FAILURE FOR ME. ITS ONLY THE INTAKE REMOVAL TO DO SO THATS WHERE ILL BE GOING. I HOPE THIS SHEADS MORE LIGHT ON THE SUBJECT FOR U
Paul Matera, MD 2004 C5 Z06 , supercharged/nitrous injected 810 HP DAILY DRIVER named SALLY