P0868 code definition
The P0868 trouble code notes an issue with the pressure of the transmission fluid.
What the P0868 code means
The P0868 code is a generic OBD-II code that detects a problem with the transmission fluid pressure. Transmission fluid serves to lubricate the transmission, and for vehicles with automatic transmissions, to cool the transmission system as well. When the powertrain control module (PCM) detects that the pressure of the transmission fluid is either too high or too low, the P0868 trouble code will be triggered.
What causes the P0868 code?
A few different things can trigger the P0868 trouble code, including:
- Insufficient transmission fluid levels due to leaks in the system
- Slipping or otherwise malfunctioning transmission
- Malfunctioning transmission high pressure pump
- Defective transmission temperature sensor
- Engine that is overheating
- Malfunctioning PCM
What are the symptoms of the P0868 code?
When the P0868 trouble code is detected, the check engine soon Warning Light will usually illuminate. The vehicle may also emit a strong burning smell from the overheating transmission, and may begin to smoke as well. The transmission may also fail, or may constantly slip.
How does a mechanic diagnose the P0868 code?
The P0868 code should be diagnosed with the assistance of a standard OBD-II trouble code scanner. A trained mechanic will use the scanner to assess the freeze frame data. This allows the technician to gather information about the P0868 code, and search for other trouble codes that may be present as well. If no drivability issues have been detected by the mechanic beforehand, the codes should be reset and the vehicle restarted, to see if the P0868 trouble code returns. If the code does not return, it was likely triggered incorrectly.
If the P0868 trouble code remains, the mechanic should first inspect the transmission fluid levels. If the fluid is low, it should be assumed that there is a leak in the system, and the mechanic should begin searching for where the leak is coming from. Depending on the location of the leak, it may be able to be repaired, and the issue resolved. However, many areas of leakage suggest further damage to the transmission, which will need to be removed and possibly rebuilt or replaced.
If the transmission fluid level is normal, the mechanic should check to see if the transmission temperature sensors are faulty. Only after checking the sensors should the technician search for more severe issues, such as transmission failure or a malfunctioning PCM.
After the problem has been identified and repaired or replaced, the codes should once again be reset, and the vehicle restarted, to make sure that the issue is fully resolved.
Common mistakes when diagnosing the P0868 code?
The most common mistake that is made during P0868 code diagnosis is the failure to follow the basic OBD-II trouble code diagnosis protocol in the right order. Not adhering to the protocol can cause anything from extra time and trouble, to misdiagnosis.
One common issue comes when mechanics fix a leak in the system, without assessing whether or not the transmission has been damaged. Failure to properly inspect the transmission during P0868 code diagnosis can cause severe issues in the transmission.
How serious is the P0868 code?
The P0868 code is very serious, because of the damage that it can cause to the transmission. Even if a car is operating normally, it should not be driven when the P0868 code is detected. Driving a car with a P0868 code has the potential to completely damage the transmission, which is not only dangerous, but requires extensive repairs.
What repairs can fix the P0868 code?
Some of the repairs for the P0868 trouble code include:
- Fixing leaks in the transmission system
- Transmission temperature sensor replacement
- Transmission high pressure pump replacement
- Transmission rebuilding or repairing
- PCM replacement
Additional comments for consideration regarding the P0868 code
PCM failure is very rare, but if the PCM does not to be replaced, it will also need to be reprogrammed.
Need help with a P0868 code?
YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.
This article originally appeared on YourMechanic.com as P0868 OBD-II Trouble Code: Transmission Fluid Pressure Low and was authored by Brady Klopfer.