P08AD: Neutral Position Sensor B Circuit/Open

A neutral position sensor tells the engine module whether a manual gearbox is in neutral, which start-stop, remote start and rev matching rely on. Sensor B is a second sensor or channel next to sensor A (P086A ff). P08AD flags an open or otherwise faulty sensor B circuit. No manufacturer documents this code publicly; Audi (sender G701) and GM (Corvette LT5) are only known to use the A codes. A GM patent shows why a B channel exists: two Hall sensors on the shift shaft give a PWM signal, and in neutral both must read the same. CARB 1968.2 (e)(15) requires circuit monitoring of such inputs. Expected effect: start-stop stays off; MIL status depends on the maker.

Symptoms

• Start-stop no longer switches the engine off
• Start system warning in the cluster
• Driving normally unaffected

Most likely causes

• Wire to the sensor broken or stretched by shift shaft movement
• Connector at the gearbox loose or corroded
• Sensor B open internally

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the fluid level and condition
2. Check the continuity of the wire between the component and the control module.
3. Read the input and output speed in live data
4. Check the connector and wiring
5. Check for other related engine codes
6. Consult the manufacturer's procedure for the transmission

Good to know

• Repair difficulty: medium

What each character of P08AD means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 8: Transmission
• AD: Specific fault in that system

Frequently asked questions

Can I keep driving with code P08AD?

Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.

What causes code P08AD?

The most common causes are: wire to the sensor broken or stretched by shift shaft movement; connector at the gearbox loose or corroded; sensor B open internally.

Related codes

• P08AENeutral Position Sensor B Circuit Range/Performance
• P08AFNeutral Position Sensor B Circuit Low
• P08B0Neutral Position Sensor B Circuit High
• P08B1Neutral Position Sensor B Circuit Intermittent/Erratic
• P086ANeutral Position Sensor A Circuit/Open

Sources

• law.cornell.edu: 13 CCR 1968.2
• patents.google.com: en
• static.nhtsa.gov: MC 10244474 0001
• patents.google.com: en

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.