P08B2: Neutral Position Sensor A/B Correlation

On a manual gearbox with two neutral sensors or two channels, the engine module compares A and B. P08B2 means they disagree: one reports neutral, the other a gear, or their values differ beyond a calibrated limit, while each may look fine electrically. No manufacturer documents P08B2 publicly. A GM patent describes exactly this layout: two Hall sensors with their own magnets on the shift shaft, whose PWM outputs must be identical in neutral as an integrity check. Audi's G701 and GM's LT5 Corvette use only the A codes. CARB 1968.2 (e)(15) requires rationality monitoring of inputs. Because neutral cannot be confirmed, start-stop and remote start stay off; usual fix is aligning or replacing the sensor.

Symptoms

• Start-stop unavailable
• Start system warning in the cluster
• Gear indicator may be blank or wrong

Most likely causes

• One of the two neutral sensors drifting or faulty
• Magnet on the shift shaft shifted or sensor misaligned after repair
• Neutral position not relearned after component replacement

What to check, in order

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

1. Check the fluid level and condition
2. Compare both signals at the same time in live data and check any recent installation work.
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 P08B2 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 8: Transmission
• B2: Specific fault in that system

Frequently asked questions

Can I keep driving with code P08B2?

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

What causes code P08B2?

The most common causes are: one of the two neutral sensors drifting or faulty; magnet on the shift shaft shifted or sensor misaligned after repair; neutral position not relearned after component replacement.

Related codes

• P086ANeutral Position Sensor A Circuit/Open
• P086BNeutral Position Sensor A Range/Performance
• P08ADNeutral Position Sensor B Circuit/Open
• P08AENeutral Position Sensor B Circuit Range/Performance
• P08B3Neutral Position Sensor B Not Learned

Sources

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

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.