Auxiliary Transmission Fluid Pump Control Circuit/Open
The P2796 code indicates that the Powertrain Control Module (PCM) has detected an open or short circuit in the control circuit of the auxiliary transmission fluid pump. This pump is typically used in hybrid or start-stop vehicles to maintain transmission fluid pressure when the engine is off. An open circuit means there is a break in the electrical path, preventing the pump from operating correctly.
1. Most Common Causes
- Faulty auxiliary transmission fluid pump
- Open or shorted wiring in the pump control circuit
- Blown fuse or relay for the auxiliary pump
- Failed PCM or transmission control module
2. Symptoms You Will Notice
- Transmission may not shift properly
- Delayed engagement when shifting into drive or reverse
- Check Engine Light illuminated
- Possible transmission overheating or slipping
3. Step-by-Step Diagnosis
Step 1: Scan for other codes and check freeze frame data.
Step 2: Visually inspect the auxiliary pump wiring and connector for damage or corrosion.
Step 3: Test the pump control circuit for continuity and voltage using a multimeter.
Step 4: Check the pump fuse and relay; replace if blown.
Step 5: If circuit is intact, test the pump itself by applying direct power and ground.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a faulty auxiliary pump can cause transmission damage due to inadequate lubrication and cooling, especially in stop-and-go traffic.
How much does it cost to fix?▼
Repair costs typically range from $200 to $600, depending on whether the pump, wiring, or module needs replacement. Labor and parts vary by vehicle.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.