P2161Vehicle Speed Sensor B Circuit Intermittent/Erratic/High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2161 flags a speed signal B that behaves in ways no real vehicle can: it collapses for a moment, jumps or reads implausibly high. GM documents the code for the transfer case output speed sensor (18OBDG04). While the truck is driven in gear without braking, a drop of the sensor speed larger than a delta threshold starts a 3-second fail timer, and five such counts store the code as Type B. GM adds that one dropout can also start the P2160 timer, so whichever runs out first is recorded. Loose connector contacts, chafed wires, metal debris on the sensor tip or a cracked tone wheel are the typical culprits. P2160 means the signal is missing altogether; P2162 compares sensor B with sensor A.
- What you may notice
- Check engine lamp, often only on rough roads
- Speedometer needle twitching
- Sporadic four-wheel-drive or shift complaints
- Likely causes
- LikelyConnector contact opening briefly under vibration
- PossibleSignal wire chafed against the transfer case or frame
- PossibleMetal debris on the magnetic sensor tip
- RareChipped or cracked tone wheel
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.