P2258

Code

Generic P — Powertrain

AIR System Control A Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 47 RU: 33

AI status

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Page language: EN

Causes

Short to battery voltage (wiring or connector shorted to B+)
Failed AIR pump, AIR solenoid/valve or AIR system relay stuck closed
Corroded or damaged connector or pin causing high resistance or unintended voltage
Blown or incorrect fuse, relay fault providing constant power
PCM/ECM internal driver fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Failed or reduced secondary air injection function (may affect cold-start emissions)
Possible rough cold idle or extended tailpipe emissions during warm-up
Failed emissions test
AIR pump may run continuously or not run depending on fault

What to check

Scan for P2258 and any related codes; capture freeze frame and readiness/EVAP/emissions data
Visual inspection of AIR pump, solenoid/valve, wiring harnesses, connectors and grounds
Check relevant fuses and relays for correct operation
Backprobe the AIR control A circuit at the component and at the PCM to measure voltage with key ON and when commanded
Measure coil or device resistance (compare to spec) and check for shorts to battery or open circuits
Check continuity to ground and for unintended battery voltage present with circuit disconnected

Signal parameters

Normal: control circuit is a switched output (typically a PWM/ground-switch or switched 12V depending on vehicle) that toggles between low and expected supply; component draws current only when commanded
Fault: circuit voltage remains at or near battery voltage when it should be low or below the PCM threshold
Expected behavior: voltage should change when PCM commands the AIR device; open/short or stuck-high will prevent proper switching
Note: exact voltage and waveform vary by vehicle — consult manufacturer wiring diagram/specs before interpreting measurements

Diagnostic algorithm

Retrieve freeze-frame data and related codes. Note engine state and conditions at code set.
Perform a visual inspection of the AIR pump, solenoid/valve, related wiring, connectors, fuses and relay. Repair obvious damage or corrosion.
With ignition ON (engine OFF), backprobe the AIR control A connector and measure voltage. Compare to battery voltage and expected behavior. If battery voltage present when circuit should be low, suspect short to B+ or stuck relay.
Disconnect AIR component (pump/solenoid). Clear codes, then command AIR on via scan tool or cycle key/engine to see if code returns. If code does not return with component disconnected, the component or its wiring is likely at fault.
Measure resistance of the AIR device (solenoid coil or pump motor) and compare to specifications. Check for internal short to battery or abnormal low resistance.
Inspect and test the AIR relay and any driver fuses. Remove or swap relay (if identical) to verify relay behavior. Check for power being supplied to circuit when it should be off.
Check wiring continuity between component and PCM, and continuity to ground. Wiggle-test harness to reproduce intermittent faults.
If wiring and component test good, backprobe PCM output. If PCM output is permanently high while other circuitry is correct, suspect PCM driver fault and consider ECU replacement after confirming with manufacturer procedures.
After repairs, clear codes and perform drive cycle or readiness test to confirm repair. Re-scan for additional codes.

Likely causes

Wiring short to B+ on the AIR control A circuit (most common)
Faulty AIR solenoid/valve or pump (internal short or internal electronics failed)
Faulty AIR system relay or stuck contacts supplying constant voltage
Corroded/loose connector at the AIR component or PCM pin
PCM output driver failure (least common)

Fault status

⚠️ Status

AIR System Control A Circuit High — PCM detects unexpectedly high voltage on the secondary air injection control A circuit. Possible short to battery, failed AIR component, relay/fuse or PCM driver fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours