Powertrain, generic · Hybrid propulsion

P0D99 Battery Charger Coupler Temperature Sensor A Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P0D99 flags a general electrical fault in temperature sensor A of the charging inlet, the element that tells the car how hot the power contacts are. At high current, contact resistance heats the pins; the reading lets the car throttle or stop charging (TE Connectivity, US10960781B2). Inlet suppliers fit resistive sensors: Phoenix Contact strings PTC elements along the AC pins and puts a Pt 1000 on each DC pin, with shutdown above +90 °C at the contact. For the third-generation smart electric drive with 22 kW charger, Mercedes defines P0D9900 as an electrical fault of the inlet contact temperature sensor; bulletin LI54.10-P-067823 traces it, like neighbouring sensor codes, to loose low-voltage plugs at the charger. Without a usable reading, charging is refused or limited. Implausible, low and high readings are P0D9A–P0D9C.

Likely causes

Loose low-voltage connector at the on-board charger (smart)
Damaged sensor wiring between inlet and charger
Temperature element in the inlet failed (usually replaced with the inlet harness)
Evaluation input in the charger module defective

Symptoms

  • High-voltage battery cannot be charged
  • Charging only at reduced power
  • Charging system fault message

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–1,200
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

charge port temperature sensorwiring harnesson board charger

Related codes

P0D9AP0D9BP0D9CP0D9DP0E5F

References: static.nhtsa.gov, patents.google.com, phoenixcontact.com.