<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: The illumination of the engine light indicates a problem with the Secondary Air Injection System Control 'B' Circuit. This could be due to a low voltage condition in the circuit.</li> <li><b>Poor Engine Performance</b>: A malfunctioning secondary air injection system can lead to reduced engine performance. This is because the system is responsible for reducing emissions by injecting air into the exhaust stream.</li> <li><b>Failed Emissions Test</b>: If the secondary air injection system is not functioning properly, the vehicle may fail an emissions test due to higher than normal levels of pollutants.</li> <li><b>Rough Idle</b>: A faulty secondary air injection system can cause the engine to idle roughly, as the air-fuel mixture may not be optimal.</li> </ul>

<ul><li>The secondary air system relay may be faulty, preventing proper operation of the air injection system.</li><li>An open or shorted harness in the secondary air system relay can disrupt the circuit and trigger the error code.</li><li>Poor electrical connections in the secondary air system relay circuit can lead to intermittent or failed communication.</li><li>A malfunctioning secondary air system pump can cause insufficient air flow, resulting in the error code.</li></ul>

<ul> <li><b>Retrieve Codes and Freeze Frame Data</b>: Connect the diagnostic scanner to the vehicle's diagnostic port. Retrieve all stored codes and pertinent freeze frame data. Write down this information for reference.</li> <li><b>Clear Codes and Test Drive</b>: Clear the codes and test drive the vehicle until the code is restored or the PCM enters readiness mode. If the code is intermittent, the condition may need to worsen for accurate diagnosis.</li> <li><b>Perform Visual Inspection</b>: Inspect related wiring and connectors for damage such as cuts, burns, or corrosion. Repair or replace any damaged wiring or connectors.</li> <li><b>Check Secondary Air Injection System Control Voltage</b>: Use a DVOM to test the secondary air injection system control voltage at the appropriate connector pin. If no voltage is detected, check system fuses and replace any blown or defective fuses.</li> <li><b>Test Circuit at PCM Connector</b>: If voltage is detected at the secondary air injection system control connector, test the corresponding circuit at the PCM connector. If no voltage is detected, suspect an open circuit between the sensor and the PCM.</li> <li><b>Inspect PCM</b>: If voltage is detected at the PCM connector, suspect a defective PCM or a PCM programming error. Consider reprogramming or replacing the PCM if necessary.</li> <li><b>Consult Technical Service Bulletins (TSB)</b>: Search for any TSBs that replicate the code, vehicle (year, make, model, and engine), and symptoms. This may provide a speedy solution to the diagnosis.</li></ul>

<p>The DTC code P2259 indicates a low voltage condition in the Secondary Air Injection System Control 'B' Circuit. This is a critical issue as it can lead to increased emissions and potential damage to the catalytic converter.</p><ul><li><b>Immediate Actions:</b> Inspect the air injection pump, relay, and associated wiring for faults.</li><li><b>Potential Risks:</b> Delayed repair can result in failed emissions tests and costly damage to the exhaust system.</li></ul>