P0AC4 on Toyota: How to Diagnose & Fix
Hybrid Powertrain Control Module Requested MIL Illumination
1 Toyota model · 1 documented issue
P0AC4 on Toyota by model: symptoms, diagnosis and fix
Toyota Customer Support Program 22TE09 covers certain 2019-2022 RAV4 Hybrid AWD and 2021-2022 RAV4 Prime vehicles produced within the program's listed periods. Excessive corrosion at the connector between the HV floor-under wire harness and rear traction-motor cable may cause AM-radio static during specified drive selections, P0AA649 and/or P1C8049 with warning messages, or a vehicle that will not start. Toyota does not describe a blanket complete shutdown while driving, loss of AWD, P0AA6/P0A7F/P0AC4 condition or universal cable part number.
Common Symptoms
- AM-radio static that begins when Drive or Reverse is selected and stops in Park
- Hybrid-system warning message or MIL with P0AA649 and/or P1C8049
- Vehicle may not start after warning indicators appear
How to Fix
Check the complete VIN with an authorized Toyota dealer and have the connector inspected under CSP 22TE09. If Toyota's condition and inspection criteria are met, the dealer repairs or replaces the affected floor-under harness and replaces the rear traction-motor cable only when the inspection standard requires it. Program coverage is eight years from first use or 100,000 miles, whichever comes first, and applies only to dealer work under the program terms. Warning messages or a no-start require prompt diagnosis; do not touch or clean a high-voltage connector. Do not order from the removed search links because the floor harness is model-year- and plant-specific.
Owner tips & cautions
- TipBring the complete VIN plus any warning-message photo or scan report; CSP eligibility and the repair path depend on production data, symptoms, DTCs and Toyota's connector inspection.
- WarningThis is a high-voltage circuit. Do not touch, disconnect, probe or clean the underbody connector; use a qualified Toyota hybrid technician.
Sources for this issue (2)
P0AC4 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0AC4 mean on a 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 it is documented across 1 model: RAV4.
What are the most common causes of P0AC4?
The most common causes of P0AC4 are: Internal hybrid powertrain control module fault, Stored hybrid system DTC requiring MIL, Communication/wiring fault, Module power/ground issue. The specific cause varies by vehicle.
How much does it cost to fix P0AC4 on a Toyota?
Repair costs vary widely with the root cause and Toyota model; each issue on this page carries its own estimate where one is published.
Looking for P0AC4 on a different make?
View P0AC4 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.