Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the part of the car that helps it switch between two-wheel drive and four-wheel drive. It's like a switch that isn't working right.
The C0090 code indicates an issue with the actuator that controls the power transfer unit in a vehicle equipped with four-wheel drive (4WD) or all-wheel drive (AWD) systems.
The power transfer unit actuator is responsible for engaging and disengaging the 4WD/AWD system. A malfunction in this actuator can prevent the vehicle from properly switching between drive modes, which can affect handling and traction.
• 4WD/AWD warning light on
• Inability to engage 4WD/AWD
• Unusual noises from the drivetrain
• Faulty power transfer unit actuator
• Wiring issues or poor connections
• Failed control module
Actuator: A device that moves or controls a mechanism or system.
4WD: Four-Wheel Drive
AWD: All-Wheel Drive
• Check for any additional codes
• Inspect the wiring and connections related to the actuator
• Test the actuator for proper operation
• Replace the faulty actuator
• Repair or replace damaged wiring
• Reprogram or replace the control module
• OBD-II scanner
• Multimeter
• Basic hand tools
$300 - $800
Moderate
• Ford Explorer
• Jeep Grand Cherokee
• Toyota 4Runner
• Regular maintenance of the 4WD/AWD system
• Inspect wiring and connections periodically
• Avoid harsh driving conditions when possible
Actuator Issue
• Avoid using 4WD/AWD until the issue is resolved
• Have the vehicle inspected by a professional as soon as possible
Check with your vehicle manufacturer for warranty coverage on drivetrain components.
This code has been associated with issues in vehicles that frequently switch between 2WD and 4WD modes.
Moderate – While the vehicle may still be drivable, it could affect handling and safety.
Driving with a malfunctioning 4WD/AWD system can be unsafe, especially in adverse weather conditions.
• Vehicle stationary
• Engine running
The power transfer unit actuator is typically located near the transmission or transfer case.
Q: Can I drive my car with this code?
A: It's possible, but not recommended, especially if you need 4WD/AWD for safety.
Q: How do I reset the 4WD/AWD system?
A: Resetting may involve disconnecting the battery or using an OBD-II scanner, but it's best to fix the underlying issue first.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
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Helpful for safer access during underbody inspection work.
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