What Does P1490 Mean?
The PCM has detected a malfunction in the secondary air injection relief solenoid valve circuit. This solenoid controls airflow in the secondary air system, which reduces cold-start emissions by injecting fresh air into the exhaust stream.
Common Causes
40%
Failed secondary air relief solenoid valve
25%
Open or short circuit in solenoid wiring harness
20%
Corroded or loose electrical connector at solenoid
10%
Stuck or binding relief valve mechanism
5%
Failed PCM solenoid driver circuit
Diagnostic Steps
1
Step 1: Locate the secondary air relief solenoid valve and inspect connector for corrosion or damage
2
Step 2: Disconnect solenoid connector and measure resistance across solenoid terminals (typically 20-50 ohms)
3
Step 3: With solenoid disconnected, check for battery voltage at harness power supply wire with ignition on
4
Step 4: Use scan tool to command solenoid on/off and listen for audible click at solenoid
5
Step 5: Check ground circuit continuity between solenoid and PCM or chassis ground
Estimated Repair Cost
$150 - $450
Parts + labor, varies by vehicle and location
The PCM has detected a malfunction in the secondary air injection relief solenoid valve circuit. This solenoid controls airflow in the secondary air system, which reduces cold-start emissions by injecting fresh air into the exhaust stream.
The most common cause of P1490 (Secondary Air Relief Solenoid Circuit Malfunction) is: Failed secondary air relief solenoid valve
Typical repair costs for P1490 range from $150 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive. This fault affects only cold-start emissions and may cause emission test failure or check engine light illumination.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1490 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control - Secondary Air Injection
Difficulty
Type
Manufacturer
Recommended Tools
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