What it means
The control circuit A of the secondary air injection system shows a voltage above the calibrated upper threshold. Likely a short to battery voltage or an open in the relay coil/output.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Secondary air injection sends air into the exhaust during cold starts to help the catalytic converter reach operating temperature. P2258 sets when the module sees control circuit A above its calibrated voltage threshold, consistent with a short to battery voltage or an open relay coil or circuit.
Common causes
Most likely first.
- Control wire shorted to battery
- Open relay coil
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light on
- Rough running or increased emissions during cold starts
- Failed emissions inspection
How to diagnose it
- Review freeze-frame data and determine whether the high reading occurs when control A is commanded on or off.
- Inspect the control A wire, relay, and connectors for corrosion, loose terminals, chafing, or contact with a battery feed.
- Use the wiring diagram to test the control wire for a short to battery voltage.
- Check relay coil continuity and switching behaviour according to service information to identify an open coil or failed relay.
- Verify the circuit and module output against the manufacturer's specification before replacing components.
Common fixes
- Clean or repair corroded terminals in the control A circuit.
- Repair wiring shorted to battery voltage or an open connection.
- Replace a secondary-air relay with an open coil or failed output.
- Repair the control circuit connection or load identified by testing.
Can I keep driving?
The vehicle is usually drivable, but secondary-air operation and cold-start emissions may be affected. Limit unnecessary cold starts and fix the fault before an emissions inspection.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.