P0821Gear Lever X Position Sensor 1 Circuit
- Generic OBD-II code · Powertrain
- Can trigger limp mode
- How the car detects it
- Gear lever X and Y position sensors detect a selector's position in two directions: on an H-gate shift and select direction (a LuK patent uses two sensors about 90° apart), on a shift-by-wire lever its two axes. P0820 covers the whole X-Y circuit, P0821–P0824 and P082A–P082F sensor 1, P089A–P08A3 a redundant sensor 2. P0821 is the general circuit fault of X sensor 1 – an open or invalid signal – for modules that do not report low and high separately. No manufacturer document available to us uses it; GM reports the same axis in finer steps as P082A, P082B and P082C. A GM patent describes checking each sensor's x value separately: an invalid value makes that sensor unusable, and with a redundant sensor 2 the car can usually go on.
- What you may notice
- Transmission warning in the cluster
- Ranges partly not selectable
- With both sensors failed the vehicle stays in P or N
- Likely causes
- LikelyX position sensor in the selector assembly faulty
- LikelySignal wire or connector open or corroded
- PossibleLiquid or dirt in the center console
- RareControl module
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.