Transmission Neutral Safety Switch Open Circuit
The transmission's neutral safety switch has an open circuit, meaning the electrical connection is broken and the ECU can't detect when the transmission is in neutral. It's like a light switch that's stuck open—the circuit can't complete, so the signal never reaches the computer.
The ECM monitors the neutral safety switch circuit for voltage continuity when the transmission selector is positioned in neutral. The switch should close and complete a ground circuit in neutral position only. If the ECM detects no signal voltage or an open circuit condition, it sets this fault code.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Neutral Switch Voltage | 0V (closed/grounded) in neutral | Open circuit / no ground signal detected |
| Circuit Resistance | Less than 5 ohms when closed | Infinite ohms or open circuit |
Code P1822 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, P1822 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.