Technical Description of OBD-II Trouble Code
The Pressure Control Solenoid C is stuck in the “On” position.
What does that mean?
This is a generic diagnostic trouble code (DTC) for transmission issues and is commonly found in OBD-II vehicles with automatic transmissions.
This can apply to various vehicle brands such as Ford, Mercury, Lincoln, Jaguar, Chevrolet, Toyota, Nissan, Allison/Duramax, Dodge, Jeep, Honda, Acura, etc. The repair steps may vary depending on the year, make, model, and powertrain configuration.
When the P0797 OBD-II trouble code is detected, it means that the Powertrain Control Module (PCM) has identified a problem with the Transmission Pressure Control Solenoid “C”. Most automatic transmissions have three solenoids: A, B, and C. The trouble codes associated with the “C” solenoid are P0795, P0796, P0797, P0798, and P0799. The specific malfunction that triggers the code determines the code set and causes the Check Engine Light to illuminate.
The Transmission Pressure Control Solenoids are responsible for regulating the fluid pressure necessary for the proper operation of an automatic transmission. The PCM receives an electronic signal based on the pressure within these solenoids. The transmission’s bands and clutches change gears by directing fluid pressure to the appropriate hydraulic circuits at the right time. The PCM controls the pressure solenoids based on signals from devices that monitor the vehicle’s speed.
The P0797 code indicates that the Pressure Control Solenoid “C” is stuck in the “On” position.
Example of a transmission pressure control solenoid:
What is the severity of this DTC?
This code typically starts as moderate in severity but can quickly escalate to a more severe level if not addressed promptly.
What are some of the symptoms of the code?
Symptoms of a P0797 trouble code may include:
What are some of the common causes of the code?
Possible causes for this P0797 transmission code may include:
What are some P0797 troubleshooting steps?
Prior to troubleshooting, it is recommended to research the Technical Service Bulletins (TSB’s) specific to the vehicle’s year, model, and transmission. This can save time by providing guidance in the right direction. Additionally, checking the vehicle records for the last fluid and filter change is advisable.
Fluid & Wiring Inspections
Begin by checking the fluid level and examining its condition for any contamination. Before changing the fluid, verify the last time the filter and fluid were changed using the vehicle records.
Next, perform a detailed visual inspection of the wiring for any obvious defects. Check the connectors and connections for security, corrosion, and damaged pins. This includes all wiring and connectors related to the transmission pressure control solenoids, transmission pump, and PCM. Depending on the configuration, the transmission pump may be electrically or mechanically driven.
Advanced Steps
The advanced steps are highly vehicle-specific and require specialized equipment for accurate execution. These procedures involve using a digital multimeter and referencing the specific technical guidelines for the vehicle. Voltage and fluid pressure requirements may vary depending on the vehicle’s model and transmission design.
Continuity Checks
Unless specified otherwise in the technical data, the normal readings for wiring and connections should show 0 ohms of resistance. Continuity checks should always be performed with the power removed from the circuit to prevent shorting and further damage. Resistance or lack of continuity indicates faulty wiring that needs to be repaired or replaced.
What are some common repairs for this code?
Possible misdiagnoses may include:
We hope that the information provided in this article has been helpful in addressing the issue with your pressure control solenoid trouble code. However, please note that this article is for informational purposes only, and the specific technical data and service bulletins for your vehicle should always take precedence.
