P2259

Code

Generic P — Powertrain

AIR System Control B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 44 RU: 36

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Page language: EN

Causes

Short to ground in AIR system control B wiring or connector
Open or high-resistance wiring / poor connector contact
Failed AIR pump solenoid / control valve (bank B)
Blown fuse or faulty relay supplying the AIR system
Corroded or damaged connector pins
Faulty ECM or driver transistor (less common)

Symptoms

Check Engine MIL illuminated (DTC P2259)
Reduced or no secondary air injection operation (increased cold-start emissions)
Possible failed emissions test
Rough idle or drivability issues during cold start (occasionally)
Diagnostic trouble codes related to secondary air system (other AIR codes)

What to check

Read freeze-frame and confirm P2259 relevance to current conditions
Scan for additional codes (P0410, P049x, P2258, etc.)
Visual inspection of AIR system wiring, connectors, and vacuum lines for damage or corrosion
Check AIR solenoid/valve connector for corrosion, bent pins or water intrusion
Verify fuse(s) and relay(s) for AIR system operation
Back-probe the control wire at the solenoid while commanding the circuit ON/OFF with a scan tool

Signal parameters

Commanded OFF (no ground from ECM): control circuit typically at battery voltage or open (approx. 12 V) — depends on system design
Commanded ON: ECM usually provides a ground-switch; expected voltage at control pin near 0–1 V when commanded ON
Short-to-ground condition: control wire near 0 V even when ECM is not commanding
Typical solenoid coil resistance: commonly 5–40 ohms (varies by vehicle) — consult vehicle spec
No current flow when fuse/relay open or if solenoid is open-circuit

Diagnostic algorithm

Connect a diagnostic scanner; confirm P2259 and capture freeze-frame and related codes.
Perform a visual inspection of AIR pump, solenoid/valve B, wiring harness, and connectors for damage, corrosion, or water intrusion.
Inspect/verify power and ground feeds: check relevant fuses and the AIR system relay operation.
Back-probe the solenoid control connector. Command AIR control B ON/OFF with the scanner and observe voltage: ON should be ~0–1 V (grounded) or as specified; OFF should be high/approx battery voltage or open.
With power removed, measure resistance of the AIR solenoid coil. Compare to spec; an open or very low (short) reading indicates a faulty solenoid.
Check for continuity to ground on the control circuit (power off). No short to ground should be present; if shorted, isolate by unplugging connectors and retesting to find the damaged section.
Wiggle test harness and connectors while monitoring signal to reproduce the fault—repair damaged wires or connectors found.
If wiring and solenoid check good, verify ECM driver output. If ECM output remains abnormal after wiring/component repair, consider ECM diagnosis or replacement per manufacturer procedures.
Clear codes and perform test drive or command cycles to confirm repair. Re-scan to ensure code does not return.

Likely causes

Damaged insulation contacting chassis ground on the control lead
Corroded connector at the AIR solenoid or harness splice
Failed solenoid coil internally shorted to ground
Failed relay or blown fuse in the AIR system power/ground circuit
ECM output driver failure (verify after wiring and component checks)

Fault status

⚠️ Status

Control circuit B for the secondary AIR system is reporting a low-voltage condition. The ECM detected the circuit at or near ground when it expected a different voltage/state, indicating a wiring short, component failure, or control driver issue.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours