Vehicle Park/Speed Signal Circuit Failure
Your vehicle's park/speed signal isn't reaching the control module properly, like a radio losing its signal. This circuit tells the car whether it's in Park and how fast it's moving.
The ECM monitors voltage signals from the park switch and vehicle speed sensors to confirm Park engagement and validate speed data. When these signals drop below expected thresholds or show inconsistent patterns, the ECU triggers a fault and disables dependent functions like cruise control.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Park Switch Voltage | 4.5-5.5V (Park engaged) | <0.5V or >5.5V continuously |
| Speed Signal Frequency | Proportional to vehicle speed (typically 0-8kHz) | No signal or erratic pulses for >2 seconds |
Code B2590 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B2590 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.