P0AC4 on Toyota
Hybrid Powertrain Control Module Requested MIL Illumination
P0AC4 on Toyota vehicles indicates hybrid powertrain control module requested mil illumination. Au7o has documented this code across 1 Toyota model — most commonly on RAV4. The hybrid powertrain control module has requested the malfunction indicator lamp be turned on due to a stored internal/hybrid system fault.
Common Causes of P0AC4
- •Internal hybrid powertrain control module fault
- •Stored hybrid system DTC requiring MIL
- •Communication/wiring fault
- •Module power/ground issue
P0AC4 on Toyota by Model
Toyota RAV4(1 issue)
- Hybrid High-Voltage Cable Connector Corrosion Causing Complete Hybrid System Shutdown2019-2022
On 5th-gen RAV4 Hybrid and RAV4 Prime models, the high-voltage cable that routes power from the front hybrid components to the rear electric motor (used for AWD) runs underneath the vehicle and is poorly protected from the elements at its rear connector. Road salt, water, and debris drive premature corrosion at the connector where it mates to the rear motor unit. As corrosion progresses, the connection degrades and can ultimately trigger a complete hybrid-system shutdown, leaving the vehicle inoperable. The out-of-warranty repair runs $5,000-$7,000+ because Toyota originally warranted the cable for only 3 years/36,000 miles versus the 8-10 year hybrid-component warranty. A class action (settled in Canada and addressed in the US) led Toyota to retroactively extend the cable warranty to match the hybrid system (up to 10 years/unlimited miles in the US settlement, 8 years/160,000 km in Canada) and reimburse owners who had already paid.
Looking for P0AC4 on a different make?
View P0AC4 across all makes →Frequently Asked Questions
What does P0AC4 mean on Toyota?▼
P0AC4 stands for "Hybrid Powertrain Control Module Requested MIL Illumination." The hybrid powertrain control module has requested the malfunction indicator lamp be turned on due to a stored internal/hybrid system fault. On Toyota specifically, this code is documented across 1 model.
What causes P0AC4 on Toyota vehicles?▼
Common causes on Toyota: Internal hybrid powertrain control module fault, Stored hybrid system DTC requiring MIL, Communication/wiring fault, Module power/ground issue. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0AC4 on a Toyota?▼
Repair costs vary widely depending on the root cause and specific Toyota model.
Which Toyota models have P0AC4 documented?▼
Au7o has documented P0AC4 on 1 Toyota model: RAV4.