P2DA1Gear Shift Control Module B Supply Voltage Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- With shift-by-wire, the selector the driver touches is an electronic module; module B is a second one, such as a further selector station or a redundant unit. Allison's 6th-generation controls show such a pair: for module 2 they list performance, lost communication, incompatibility and invalid data (P085E, U0291, U0333, U0592), but no supply codes. P2DA1 means the 12 V feed of module B, as measured by the module or the transmission controller, is below its lower limit. No manufacturer documents P2DA1 publicly. Audi's selector lever J587 on 2019–21 A6/A7 shows how much depends on this voltage check: its evaluation logged faults and blocked range selection until new software was loaded. Battery, fuse, feed wire and ground come first.
- What you may notice
- Shifter warning in the instrument cluster
- Range selection at the second selector ignored, vehicle stays in P
- Fault appears together with other low-voltage codes
- Likely causes
- LikelyWeak 12 V battery or voltage dip during cranking
- PossibleCorroded ground, loose connector or high-resistance feed to module B
- PossibleFuse for module B blown or with poor contact
- RareVoltage evaluation in module software too strict
- Repair
- Medium · Often possible to do yourself.Typical cost: €20 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.