Fault code P285A is called “Clutch “B” Pressure Disengagement Performance” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P285A
OBD-II fault code P285A is a generic code, which is defined as “mismatch clutch release characteristic “B””. It is set when the transmission control module (PCM) detects a general malfunction.
Signals from switches and sensors control the clutch pressure control solenoid. Therefore, the clutch pressure is adjusted according to the engine load and the driving mode of the vehicle. This makes it possible to control the hydraulic clutch pressure with high precision and achieve a smoother shifting of gears.
In a fully functional system, the transmission must disengage when stopped. If the transmission fails to disengage properly, fault code P285A will be stored.
This can occur for many reasons, although the error indicates an electrical malfunction. Sometimes it appears due to mechanical causes.
Symptoms of vehicle malfunctions
The main signal that an error P285A has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- Check engine control lamp on the control panel will light up (the code will be written in the memory as a malfunction).
- Poor acceleration.
- Floating revolutions during acceleration.
- Increased fuel consumption.
- The vehicle may go into failure or emergency operation mode.
The severity of fault code P285A is usually medium, but it can quickly become severe. Gearshift problems may occur, creating a safety hazard.
Factors that can cause this error code
The error code P285A can mean that one or more of the following problems have occurred:
- Clutch pressure control valve is defective.
- Fuse or fusible link is blown.
- Corroded or damaged connector.
- Faulty or damaged wiring harness.
- Poor electrical connection in circuit.
- Mechanical failure of transmission.
- Sometimes faulty PCM module is the cause.
How to fix or reset OBD-2 code P285A
Some suggested steps for troubleshooting and fix the error code P285A:
- Inspect the wiring for damage, abrasions, breaks, and shorts. If wiring is damaged, repair or replace it.
- Check fuses or fusible links.
- Clear any diagnostic trouble codes from the PCM and test drive to see if diagnostic trouble code P285A returns.
- Check the clutch pressure control valve.
- If all is OK, the PCM may need to be replaced and reprogrammed.
Diagnose and repair of problems
To rule out all possibilities for error P285A, visually inspect the wiring as well as the connectors. Check all fuses in the system and replace blown fuses if necessary.
Locate the diagnostic connector, connect a scan tool, and retrieve all stored codes and data. Write this information down, as it may help you in further diagnosis. Delete the codes and test drive the vehicle to see if code P285A appears again after resetting.
Locate the clutch pressure control valve and inspect for obvious physical damage. Perform a thorough visual inspection, for obvious defects such as scratches, scuffs, exposed wires, or burn spots.
If during the inspection you find that the power supply or ground is missing, you may need to check the continuity of the circuit. A continuity check should always be performed with the power disconnected.
Normal readings for wiring and connections should be 0 ohms of resistance. Resistance or no continuity indicates faulty wiring that is open or shorted and requires repair or replacement.
It is not unreasonable to check the system’s fuses when the P285A error occurs. Fuses that may appear normal when first tested may fail when the circuit is under load.
On which vehicles does this problem occur most frequently
Fault code P285A can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
- BMW
- Mitsubishi
- Nissan (Juke, Note, Qashqai, Sentra, Versa)
Fault code P285A can sometimes be found with other errors. The most common are the following: P2853, P2854, P2855, P2856, P2857, P2858, P2859.