2023 Tesla Model Y

Tesla Model Y Rear Motor Overtemperature P0C46 — Coolant Pump Cavitation

P0C46 DI_a107 DI_a112 Published 2025-01-14 Updated 2025-01-14
Tesla Model Y P0C46 motor overheat coolant pump cavitation thermal management

2023 Tesla Model Y Performance presented with power limiting and 'Motor Overheating — Power Reduced' on highway. P0C46 stored. Coolant levels normal. Root cause was cavitation in the rear motor coolant pump due to micro-bubble accumulation from an improper coolant flush procedure.

← Back to Case Library
The Problem
2023 Tesla Model Y Performance (28,900 miles) brought in after repeated power reduction events on highway drives exceeding 20 minutes. Dashboard shows 'Motor Overheating — Power Reduced'. Fault clears after 30-minute cool-down but returns on next extended drive. P0C46 (Electric Motor Stator Winding Overtemperature) and two DI motor fault codes stored. Coolant reservoir full.
Diagnostic Procedure
  1. 1. Confirm codes. P0C46 present with DI_a107 and DI_a112 — all pointing to rear motor thermal management.
  2. 2. Check coolant pump operation. Pump runs during HV active, but flow rate appears low. Coolant inlet to rear motor reads 28°C while outlet reads 61°C — 33°C delta is excessive for light load conditions.
  3. 3. Inspect coolant for air bubbles. Small air pocket visible at reservoir cap when engine bay opened after operation — indicates trapped air in the circuit.
  4. 4. Review service history — shop notes indicate coolant flush performed 2 months prior. Improper bleed procedure after flush left a micro-bubble pocket in the rear motor cooling circuit.
  5. 5. Perform Tesla cooling system bleed procedure: vehicle jacked at specified angle, bleed sequence run via service mode, coolant topped off.
  6. 6. After bleed: coolant pump audibly increases flow. Inlet-to-outlet delta drops to 12°C under same load condition.
  7. 7. Highway simulation — 45 minutes at sustained load. No fault return. P0C46 does not reappear.
Resolution & Root Cause
Cooling system properly bled per Tesla service procedure. Air pocket removed. Coolant pump flow restored. Motor temperatures normal under sustained load.
💡 Key Lesson
A properly filled coolant reservoir does not rule out air in the circuit. After any coolant service on Tesla Model Y, always perform the full bleed procedure with vehicle at the correct angle. A trapped air pocket causes pump cavitation, reducing flow to the rear motor and triggering P0C46 under sustained load — despite the reservoir appearing full.
About This Case

This case was solved remotely by an HVDesk specialist with 15+ years of hands-on experience across major EV platforms including Tesla, Hyundai/Kia, Volkswagen ID series, BMW i-series, and Ford EVs. The procedure was provided as structured remote support to an independent auto repair shop.