Secondary Air Injection System Control "A" Circuit High
P2258 indicates the Secondary Air Injection (SAI) system control circuit 'A' is reading a voltage that is higher than the expected range. This prevents the engine computer from properly controlling the secondary air injection pump, which helps reduce emissions during cold start and catalyst warm-up.
What You Might Notice
- Secondary air injection system disabled or not functioning
- Check engine light illuminated
- Unusual or rattling noises from engine compartment
- Failed emissions test
- No obvious drivability issues in most cases
Most Common Causes
- 1
Blown fuse or relay
A blown secondary air injection system fuse or defective relay prevents proper control voltage from reaching the pump motor circuit.
- 2
Open or shorted control circuit
Broken wiring, loose connectors, or corrosion in the SAI pump control circuit causes incorrect voltage readings at the PCM.
- 3
Defective SAI pump motor
A failed secondary air injection pump motor or internal pump winding short creates abnormal resistance in the control circuit.
- 4
PCM programming error or defective module
Engine computer software corruption or a faulty powertrain control module may misinterpret circuit voltage as excessive.
How to Diagnose It
- 1
Check Blown fuse or relay — A blown secondary air injection system fuse or defective relay prevents proper control voltage from reaching the pump motor circuit.
- 2
Check Open or shorted control circuit — Broken wiring, loose connectors, or corrosion in the SAI pump control circuit causes incorrect voltage readings at the PCM.
- 3
Check Defective SAI pump motor — A failed secondary air injection pump motor or internal pump winding short creates abnormal resistance in the control circuit.
- 4
Check PCM programming error or defective module — Engine computer software corruption or a faulty powertrain control module may misinterpret circuit voltage as excessive.
How to Fix It
- 1
Inspect and replace SAI system fuse
Locate the secondary air injection fuse in the fuse box, inspect for blown condition, and replace with correct amperage rating if blown. Verify fuse box diagram in owner's manual.
- 2
Test and repair control circuit wiring
Use a DVOM to check for continuity and shorts in the SAI pump control wires between the PCM and pump motor. Repair any broken insulation, loose terminals, or corroded connections.
- 3
Replace secondary air injection pump
If control circuit voltage testing confirms excessive voltage with good wiring, the pump motor is likely shorted and must be replaced as an assembly.
- 4
PCM reprogramming or replacement
If all circuit components test normal, have a dealer reprogram the engine computer or replace the PCM if corruption is confirmed through diagnostic testing.
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