Secondary Air Injection System Control Circuit Low
The P2259 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the control circuit of the secondary air injection system. This system pumps fresh air into the exhaust to reduce emissions during cold starts. A low circuit voltage suggests a short to ground, open circuit, or faulty component such as the relay, pump, or wiring.
01. Most Common Causes
- Faulty secondary air injection pump relay
- Open or shorted wiring in the control circuit
- Blown fuse for the secondary air injection system
- Failed secondary air injection pump motor
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Failed emissions test
- Possible rough idle or hesitation on cold start
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P2259 and check for related codes.
Step 2: Inspect the secondary air injection pump fuse and relay; replace if blown or faulty.
Step 3: Test the control circuit wiring for shorts or opens using a multimeter.
Step 4: Check the secondary air injection pump operation by applying battery voltage directly.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the vehicle may fail an emissions test and the Check Engine Light will stay on. It's best to repair it soon to avoid potential catalytic converter damage.
How much does it cost to fix?▼
Typically $50-$150 for parts like a relay or fuse, plus labor if needed. A pump replacement can cost $200-$400.