P2259 — Secondary Air Injection System Control "B" Circuit Low
powertrain (engine/transmission)
Is it safe to drive?
Short-term driving is OK In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.
How to diagnose with an OBD scanner
- Read the code and freeze frame Connect an OBD2 scanner, confirm P2259 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
- Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
- Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the secondary air injection system control "B" for damage, corrosion, chafing or poor contact.
- Subsystem check Check for supply voltage at the secondary air injection system control "B" connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
- Subsystem check Measure reference voltage, ground and signal continuity at the component connector.
- Subsystem check Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
- Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2259 does not return.
Approximate repair cost
Repair cost depends on which component actually failed. Typical scenarios for P2259 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the faulty sensor or actuator: $150–$500; Control module repair: $300–$1,000. Overall, fixing P2259 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.
Common questions
What are the symptoms of P2259?
Drivers most often notice: Check Engine Light on, increased fuel consumption in some cases, the affected system operates intermittently or not at all, possible limp mode depending on the affected component.
Is it safe to drive with P2259?
In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.
How much does it cost to fix P2259?
Repair wiring or connectors — $80–$250; Replace the faulty sensor or actuator — $150–$500; Control module repair — $300–$1,000. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.
What does OBD2 code P2259 mean?
Secondary Air Injection System Control "B" Circuit Low (P2259): a powertrain (engine/transmission) fault affecting the sensor and actuator circuits. The car is usually drivable while you plan the repair. Most often caused by open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.
How do I diagnose P2259 myself?
Start with a scan: confirm P2259, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the secondary air injection system control "B", and verify the suspect component against live data before buying parts.
What does P2259 mean?
When P2259 appears on a scan, it means the control module has flagged a problem in the sensor and actuator circuits: secondary air injection system control "B" circuit low. The fault sits in the powertrain (engine/transmission) group of the OBD2 standard.
“Circuit low” means the voltage on the secondary air injection system control "B" circuit stays below the expected minimum — close to ground. The usual physical reasons are a short to ground, a chafed wire touching metal, a missing supply voltage, or a failed component dragging the signal down.
To set P2259, the control module compares live readings of the sensor and actuator circuits against calibrated limits, usually over several drive cycles. Alongside the code it stores a freeze frame — a snapshot of rpm, load, coolant temperature and vehicle speed at the moment of failure. Reading that snapshot first saves diagnostic time.
What causes P2259?
- failed secondary air injection system control "B" pulling the signal low
- signal wire shorted to ground (chafed insulation)
- missing supply voltage to the secondary air injection system control "B"
- corroded, loose or damaged connector
- blown fuse feeding the circuit
- poor ground connection
- control module driver fault
- faulty sensor or actuator of the affected circuit
Common symptoms of P2259
- Check Engine Light on
- increased fuel consumption in some cases
- the affected system operates intermittently or not at all
- possible limp mode depending on the affected component
How to diagnose P2259
- Connect an OBD2 scanner, confirm P2259 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
- Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
- Visually inspect the wiring harness and connectors related to the secondary air injection system control "B" for damage, corrosion, chafing or poor contact.
- Check for supply voltage at the secondary air injection system control "B" connector first; then measure resistance from the signal wire to ground — near-zero ohms confirms a short to ground in the harness.
- Measure reference voltage, ground and signal continuity at the component connector.
- Wiggle-test the harness while watching the signal in live data — dropouts reveal broken wires.
- Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P2259 does not return.
How to fix P2259
Start with the cheapest and most common causes before replacing expensive parts:
- Repair wiring or connectors — $80–$250
- Replace the faulty sensor or actuator — $150–$500
- Control module repair — $300–$1,000
How much does it cost to fix P2259?
Repair cost depends on which component actually failed. Typical scenarios for P2259 (parts and labor, USD, independent shop rates):
- Repair wiring or connectors: $80–$250
- Replace the faulty sensor or actuator: $150–$500
- Control module repair: $300–$1,000
Overall, fixing P2259 usually costs between $80 and $1,000. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.
Can you drive with P2259?
In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.