Secondary Air Injection System Control Circuit Low
The P2257 code indicates that the powertrain control module (PCM) has detected a low voltage condition in the control circuit for the secondary air injection system. This system pumps fresh air into the exhaust to reduce emissions during cold starts. A low circuit condition typically points to a short to ground, open circuit, or faulty relay, preventing the air pump from operating correctly.
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 PCM (rare)
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: Scan for codes and verify P2257 is present.
Step 2: Inspect the secondary air injection pump relay and fuse; replace if faulty.
Step 3: Check wiring and connectors for damage, corrosion, or shorts to ground.
Step 4: Test the control circuit voltage at the pump connector with a multimeter.
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 drivability issues.
How much does it cost to fix?▼
Typically between $50 and $150 for parts like a relay or fuse, plus labor if diagnosed by a shop. Wiring repairs may add cost.