What Does P0492 Mean?
The PCM has determined that the secondary air injection (SAI) system is not delivering sufficient airflow to the exhaust on Bank 2. Similar to the Bank 1 counterpart, this code means the expected oxygen enrichment on the Bank 2 side was not detected during SAI operation, indicating restricted airflow or a bank-specific component failure. On V-configuration engines, this isolates the fault to the Bank 2 delivery path.
Common Causes
35%
Clogged or stuck secondary air injection check valve on Bank 2, preventing airflow from reaching the exhaust manifold
30%
Blocked or collapsed Bank 2 SAI delivery hose or pipe from carbon, rust, or moisture-induced corrosion
20%
Failed secondary air pump providing insufficient airflow to adequately supply both banks simultaneously
15%
Cracked or disconnected SAI hose on the Bank 2 side causing air to leak before reaching the exhaust manifold
Diagnostic Steps
1
With the engine cold, start and listen for SAI pump activation. If the pump runs, disconnect the SAI hose at the Bank 2 check valve to verify airflow is reaching that bank. Compare airflow volume to Bank 1 if accessible.
2
Remove and inspect the Bank 2 check valve. The internal flap should move freely. Carbon buildup or a stuck diaphragm will prevent airflow. Blow through the valve from the pump side to confirm it opens; it should seal from the exhaust side.
3
Inspect the Bank 2 delivery pipe for internal corrosion or carbon blockage. On many V6/V8 engines, the Bank 2 pipe routes underneath the intake manifold where it is susceptible to hidden corrosion and damage.
4
Check all SAI hose connections on the Bank 2 side for cracks, loose clamps, or complete disconnection. Age-hardened rubber hoses commonly split or blow off, diverting air away from the exhaust.
5
If Bank 1 flow is adequate but Bank 2 is restricted, the fault is isolated to the Bank 2 delivery path. Replace the check valve and/or delivery pipe as needed, then clear codes and verify operation on the next cold start.
Estimated Repair Cost
$200 - $800
Parts + labor, varies by vehicle and location
The PCM has determined that the secondary air injection (SAI) system is not delivering sufficient airflow to the exhaust on Bank 2. Similar to the Bank 1 counterpart, this code means the expected oxygen enrichment on the Bank 2 side was not detected during SAI operation, indicating restricted airflo...
The most common cause of P0492 (Secondary Air Injection System Insufficient Flow Bank 2) is: Clogged or stuck secondary air injection check valve on Bank 2, preventing airflow from reaching the exhaust manifold
Typical repair costs for P0492 range from $200 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Insufficient secondary air flow on Bank 2 affects cold-start emissions compliance and catalytic converter warm-up. There is no immediate safety risk, but prolonged failure may accelerate catalyst degradation on the affected bank.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0492 to identify the root cause.
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Quick Info
Category
Powertrain
System
Secondary Air Injection System
Difficulty
Type
Generic (SAE)
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