Secondary Air Injection System Control 'A' Circuit Low
The P2257 code means the vehicle's onboard diagnostic system has detected: Secondary Air Injection System Control 'A' 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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What Are the Symptoms of P2257?
- Check Engine Light on
- Failed emissions test
- No noticeable drivability symptoms
- Air pump may not activate on cold start
- Slight rough cold idle
What Causes P2257? (Most Likely First)
- Short to ground in secondary air pump relay circuit Very High
- Failed secondary air pump relay High
- Wiring damage to air pump control circuit Moderate
- ECM driver circuit shorted Low
Can I Still Drive with P2257?
Yes, but fix soon. P2257 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
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.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2257?
-
Check secondary air pump relay operation
-
Measure relay control circuit voltage
-
Inspect wiring for shorts to ground
-
Test ECM output at the relay connector
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Which Vehicles Commonly Get P2257?
- 2008-2018 Toyota Tundra 5.7L
- 2010-2018 Subaru Outback 2.5L
- 2009-2017 Volkswagen Tiguan 2.0T
- 2008-2016 Toyota Sequoia 5.7L
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