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 computer in your car is having trouble talking to a part that helps move the transmission fluid. It's like when a walkie-talkie isn't working right and you can't hear the other person.
The P2798 code indicates a problem with the electrical circuit that controls the auxiliary transmission fluid pump, which is crucial for maintaining proper transmission fluid pressure.
The P2798 code is triggered when the Powertrain Control Module (PCM) detects a low voltage condition in the control circuit of the auxiliary transmission fluid pump 'A'. This pump is responsible for ensuring that the transmission fluid is circulated properly, especially in vehicles with start-stop systems or hybrid vehicles.
• Check Engine Light is on
• Transmission overheating
• Poor fuel economy
• Erratic transmission shifting
• Faulty auxiliary transmission fluid pump
• Damaged or corroded wiring or connectors
• Blown fuse related to the pump circuit
• Faulty PCM
PCM: Powertrain Control Module, the computer that controls the engine and transmission.
Auxiliary Transmission Fluid Pump: A pump that helps circulate transmission fluid, especially in hybrid vehicles.
• Use an OBD-II scanner to confirm the code.
• Inspect wiring and connectors for damage or corrosion.
• Check the fuse related to the pump circuit.
• Test the auxiliary transmission fluid pump for proper operation.
• Replace or repair damaged wiring or connectors.
• Replace the blown fuse if necessary.
• Replace the faulty auxiliary transmission fluid pump.
• Reprogram or replace the PCM if needed.
• OBD-II scanner
• Multimeter
• Basic hand tools (screwdrivers, wrenches)
$150 - $500
Moderate
• Toyota Prius
• Ford Fusion Hybrid
• Chevrolet Volt
• Regularly inspect and maintain the transmission system.
• Ensure proper electrical connections and wiring integrity.
• Perform routine transmission fluid checks and changes.
Sensor Issue
• Avoid driving the vehicle until the issue is resolved to prevent further damage.
• Consult a professional mechanic for an accurate diagnosis and repair.
Check with your vehicle manufacturer as this issue may be covered under the powertrain warranty.
This code has been more prevalent in hybrid and electric vehicles due to their reliance on electric pumps for transmission fluid circulation.
Moderate – Addressing this issue promptly can prevent transmission damage.
Driving with a malfunctioning transmission pump can lead to transmission failure, which may be unsafe.
• Vehicle at operating temperature
• Transmission fluid level checked
The auxiliary transmission fluid pump is typically located near the transmission housing.
Q: Can I drive with a P2798 code?
A: It's not recommended to drive with this code as it can lead to transmission damage.
Q: How can I reset the P2798 code?
A: The code can be reset with an OBD-II scanner, but it will likely return if the underlying issue is not fixed.
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