Secondary Air Injection System Control 'B' Circuit Low
The P2259 code means the vehicle's onboard diagnostic system has detected: Secondary Air Injection System Control 'B' Circuit Low. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $500 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Failed emissions test
- No noticeable drivability symptoms
- Bank 2 air injection not working
- Possible cold start rough idle
Probable Causes (Ranked by Likelihood)
- Short to ground in B control circuit wiring Very High
- Failed B control relay High
- Wiring damage to B circuit Moderate
- ECM B driver circuit fault Low
Step-by-Step Diagnostic Procedure
-
Check B control relay operation
-
Measure B circuit voltage at relay
-
Inspect B wiring for shorts
-
Test ECM B output signal
Frequently Asked Questions
What is the secondary air injection system?
The secondary air injection system pumps fresh air into the exhaust during cold start to help the catalytic converter reach operating temperature faster and reduce cold-start emissions.
Will this code cause my car to fail emissions?
Yes, secondary air injection codes will almost always cause an emissions test failure because the system is specifically designed to reduce startup emissions.
Can I delete the secondary air injection system?
Removing or disabling the secondary air system is illegal in most jurisdictions as it is a required emissions control component. The system should be repaired to maintain compliance.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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