Gear Shift Position Circuit Intermittent
Your transmission's gear position sensor is sending an unstable or flickering signal to the engine computer, like a light switch that keeps turning on and off randomly. This prevents the ECU from reliably knowing which gear you're in.
The ECU monitors voltage signals from the gear shift position sensor (typically a potentiometer or Hall-effect sensor) to determine current gear selection. The sensor should produce a stable, consistent voltage for each gear position. An intermittent fault means the signal is dropping out or fluctuating unpredictably, causing the ECU to lose confidence in the gear position reading.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor voltage stability | Steady 0.5-4.5V per gear position | Voltage drops below 0.2V or fluctuates >0.5V within 100ms |
| Signal continuity | Continuous signal present | Intermittent signal loss or dropout events |
Code P0918 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0918 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.