Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the electric pump that helps move the transmission fluid. It's like when a toy's motor isn't working properly because the battery is too low.
The code indicates a low voltage or electrical issue in the circuit that controls the phases U, V, and W of the electric or auxiliary transmission fluid pump.
The P0C21 code is triggered when the Powertrain Control Module (PCM) or Transmission Control Module (TCM) detects a low voltage condition in the electric or auxiliary transmission fluid pump's U-V-W phase circuit. This pump is crucial for maintaining the correct pressure and flow of transmission fluid, which is essential for the proper operation of the transmission system.
• Check Engine Light is on
• Transmission may not shift properly
• Reduced fuel efficiency
• Faulty electric/auxiliary transmission fluid pump
• Damaged or corroded wiring or connectors in the pump circuit
• Faulty PCM or TCM
PCM: Powertrain Control Module
TCM: Transmission Control Module
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the electric/auxiliary transmission fluid pump for proper operation.
• Replace or repair damaged wiring or connectors.
• Replace the faulty electric/auxiliary transmission fluid pump.
• Reprogram or replace the PCM/TCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$200 - $800
Moderate
• Toyota Prius
• Chevrolet Volt
• Ford Fusion Hybrid
• Regular maintenance checks
• Ensure proper electrical connections
• Use quality replacement parts
Electrical Circuit Issue
• Avoid driving the vehicle until repaired to prevent further damage.
• Consult a professional mechanic for accurate diagnosis and repair.
Repairs may be covered under powertrain warranty if the vehicle is still within the warranty period.
This code has been associated with hybrid and electric vehicles due to their reliance on electric pumps for transmission fluid circulation.
Moderate – It is advisable to address this issue soon to avoid potential transmission damage.
Driving with this code may lead to transmission failure, which can be dangerous. Always prioritize safety and repair issues promptly.
• Vehicle at operating temperature
• Engine running
The electric/auxiliary transmission fluid pump is typically located near the transmission assembly.
Q: Can I drive my car with a P0C21 code?
A: It's not recommended to drive with this code as it can lead to transmission damage.
Q: How can I clear the P0C21 code?
A: The code can be cleared with an OBD-II scanner after the issue is fixed, but it may return if the problem persists.
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