U0240Lost Communication With Entrapment Control Module B
- Generic OBD-II code · Network
- How the car detects it
- U0240 flags the second anti-trap unit, entrapment control module B, as missing on the network. Where a vehicle has more than one automatically closing panel, for example a sunroof plus a power sliding door, each may carry its own reversal electronics, and B denotes one of them as assigned by the maker; no manufacturer documents U0240 publicly. The protection itself is defined by FMVSS 118, which limits the squeezing force and requires reversal before a test rod is trapped, and by the reversal logic in anti-pinch modules that compare motor current with a learned profile. GM's lost communication logic still applies: a periodic status message stays away with supply at 9-16 V. Pair with U0239 for module A. Automatic closing may be disabled; no MIL.
- What you may notice
- Automatic close function of a panel disabled
- Panel only moves while the switch is held
- Likely causes
- LikelyModule B without power or ground
- PossibleWiring broken in a moving harness (sliding door, roof frame)
- RareEntrapment control module B faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €40 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.