P2257

Code

Generic P — Powertrain

AIR System Control A Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 49 RU: 36

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Page language: EN

Causes

Open or high-resistance wiring in AIR control circuit
Short to ground on the control (driver) wire
Failed AIR pump, pump motor or control solenoid/valve
Blown fuse or failed relay supplying the AIR system
Corroded or loose connector or poor ground at pump/solenoid
Low battery voltage or charging system problem during test

Symptoms

Malfunction Indicator Lamp (MIL) illuminated with P2257 stored
Reduced or no secondary air injection during cold start — possible higher emissions or failed emissions test
Secondary air pump not running / audible pump silence on startup
Rough cold idle or extended rich/burn-off period (depending on vehicle)
Sometimes no obvious drivability symptoms aside from MIL

What to check

Retrieve freeze-frame and live data with a scan tool; confirm P2257 and any related AIR or emission codes
Visual inspection of AIR pump, solenoid/valve, wiring harness and connectors for corrosion, heat damage, loose pins or water entry
Check related fuses and AIR pump/relay operation
Listen for AIR pump operation during key-on and engine start (some vehicles run pump momentarily)
Use a DVOM to check supply voltage and ground at the pump/solenoid connector with key ON and while commanding the circuit ON with a scan tool
Measure coil resistance of the AIR solenoid/pump motor and compare to manufacturer specs

Signal parameters

Refer to factory data for exact values — generic expected ranges:
Supply voltage to AIR system: battery voltage (~11–14.5 V) with key ON/engine running (if fused and powered)
Control/driver circuit: near 0 V when driver is sinking to ground (vehicle-specific); open/low if circuit shorted to ground or open
Solenoid coil resistance: typically low single digits to tens of ohms (example range 2–30 Ω) — consult service data for exact value
No-load current for pump motor varies by design; abnormal high or no current indicates fault

Diagnostic algorithm

Confirm DTC: connect a scan tool, record freeze-frame/live data, and check for additional codes (P0410, P0411 etc.).
Visual inspection: examine AIR pump, solenoid, vacuum lines (if used), wiring harness and connectors for obvious damage, corrosion or water intrusion. Repair or clean connectors as needed.
Check fuses/relays: inspect and test related fuse(s) and AIR pump relay; replace if faulty.
Power/ground test: with key ON and connector disconnected, verify battery voltage at the supply terminal of the connector and a good chassis/ECM ground at the ground terminal.
Activate circuit: command the AIR pump/solenoid ON with scan tool while monitoring the control/driver voltage. Note expected behavior per factory data. If no change, isolate wiring between ECM and component.
Component test: measure resistance of solenoid coil or pump motor and compare to spec. Apply regulated bench/vehicle battery voltage to the pump/solenoid (with proper safety and fuse protection) to confirm operation.
Wiring isolation: if supply and component are good but control is low, check for short to ground or open in the driver circuit; back-probe and trace wiring; repair broken wires or shorted insulation.
ECM check: if wiring and component test good, test ECM driver output or consult manufacturer procedures/tech support before replacing ECM.
Clear codes and perform a cold-start self-test / road test to verify repair.

Likely causes

Corroded/loose connector at AIR pump or solenoid
Blown fuse or failed AIR relay
Failed AIR pump motor or solenoid coil
Wiring short to ground or open circuit between ECM and AIR component
Poor ground at pump/engine body (ground strap)

Fault status

⚠️ Status

AIR System Control A Circuit Low — control circuit voltage below expected; check fuses/relays, connectors, wiring and AIR pump/solenoid. Possible open, short-to-ground, or failed component.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours