What the P0895 code means
Computer controlled automatic transmissions change gear ratios to increase or decrease vehicle speed and optimize engine performance and fuel efficiency. In a P0895 code instance, the PCM has registered a defect or abnormality in the shift time between individual gears.
What causes a P0895 code?
While the parameters and conditions to set a P0895 code can vary greatly between manufacturers and even models from the same make, practically every application takes in information on throttle position, vehicle speed, engine speed and engine load to determine a proper gear ratio. If the gear ratio detected doesn’t match the desired gear ratio from the PCM, a trouble code will be stored and the malfunction indicator lamp (MIL) will illuminate. Some makes/models may require multiple failure cycles before the MIL will illuminate.
The P0895 code is commonly caused by a failed shift solenoid, blocked hydraulic passages inside the transmission, internal transmission failures, low transmission fluid level, faulty transmission control module or dirty/contaminated transmission fluid.
What are the symptoms of a P0895 code?
There may be no detectable symptoms at all, or symptoms can include:
- Failure to shift from or to any particular gear
- Harsh shifts
- Transmission slippage
- Transmission overheating
- Poor fuel economy
- Lack of power
- Stored trouble code
- Illuminated MIL
Other gear ratio related codes may be stored along with P0895.
How does a mechanic diagnose a P0895 code?
Virtually every automatic transmission-equipped vehicle since the mid 80s has used a computer-controlled automatic transmission design.
An OBD-II powertrain control module (PCM) takes in information on vehicle speed, engine/turbine speed and transmission output speed, using that to calculate the proper gear ratio for best fuel efficiency, engine performance and engine/transmission longevity. The PCM takes this input data and uses specially designed shift solenoids to initiate upshifts and downshifts. These shifts occur via fluid transfer between the hydraulic circuits and fluid passages between sets of corresponding gears.
If multiple stored gear ratio codes are found, they may indicate that transmission component slippage or delayed engagement conditions have been registered. Automatic transmissions use a high pressure pump, driven by the torque converter, to keep fluid circulating through hydraulic circuits and passages in the transmission housing and valve body. A P0895 code or related codes may be stored when internal transmission pressure is insufficient to actuate gear changes.
A scanner/code reader and digital volt/ohmmeter are both required for a successful diagnosis of this code.
Any transmission diagnosis should start with an inspection of the transmission fluid via the dipstick. Ensure the fluid level is within manufacturer’s recommendations and that fluid is in good condition. Fluid that smells burned or appears dirty should be a trouble sign.
Burned-smelling Automatic Transmission Fluid (ATF) indicates that the transmission has overheated due to being operated at a low fluid level, and internal mechanical damage may be present.
In the event of fluid that smells or appeared burned, drop the transmission pan and check for any clutch material or other debris.
If debris is found, a rebuild of hard and soft parts, fluid flush/replacement and a new torque converter will be necessary for the transmission to function properly. If debris is not found, start a visual inspection of internal wiring and connectors. Look for shorted or burned wiring, and replace/repair as needed.
If all wiring, connectors and components appear to be in good condition, connect the scanner to the diagnostic port. Record any stored trouble codes and freeze frame data. This information can be helpful in tracking down an intermittent condition.
Clear all codes and test drive the vehicle to see if the code returns.
If codes do not return, there may be an intermittent condition. Intermittent conditions may sometimes need to be allowed to worsen and return in order to make a correct diagnosis.
If ATF appears to be in good condition but the transmission fluid level is low, add enough fluid to locate the leak. Cleaning the bottom of the transmission pan and dipstick tube with brake cleaner, then spraying the area with flour cooking spray or aerosol foot powder can be useful in finding leaks.
If the transmission functions normally after adding fluid and the code doesn’t return, it may have been caused by transmission slippage due to the low fluid level/pressure. If the code returns and the transmission continues to slip or show delayed engagement, check the pump pressure with a manual pressure gauge.
Find a hydraulic pressure diagram for the vehicle in question, and thread the end of your gauge to the appropriate port on the transmission housing, in order to record pump pressure..
Compare your readings with factory specs and repair accordingly. Low pump pressure can be due to a defective pump, failed shift solenoids, failed electronic pressure regulator or clogged internal passages. Pump replacement requires removal and partial disassembly of the transmission.
If the code returns and the transmission seems to be operating normally, use the digital volt/ohmmeter to check reference voltage and ground signals at the shift solenoid. If either ground circuits are reference voltage read as “open,” check for continuity. Be sure to disconnect any related control modules before checking circuit resistance, to avoid controller damage.
Repair/replace system circuits and connectors as needed, and retest the system to see if repairs were successful. Locate a factory wiring diagram for the shift solenoid in question, test all related circuits and the solenoid itself for resistance/continuity. Compare your readings with factory specs.
Repair/replace any circuits, connectors and/or components that do not match factory specs. Retest the system to see if repairs were successful.
If all system circuits seem to be intact, connect the scanner to the diagnostic port and see if you can manually activate the shift solenoid in question.
If the shift solenoid seems to function properly and all other circuits comply with factory specs, suspect a defective PCM. Remember, though, that PCMs rarely fail and a replacement will require reprogramming.
Common mistakes while diagnosing P0895 code
It’s been reported that internal transmission failures often cause this code. Shift solenoid malfunctions are misdiagnosed this way, and solenoids are replaced in error.
How serious is a P0895 code?
A P0895 code can be triggered by several different causes, which can result in anything from a poorly-performing transmission to complete transmission failure.
What repairs can fix a P0895 code?
- Replacement of transmission solenoid
- Flush/refill of ATF
- Rebuild of transmission and torque converter
Addition comments for consideration for P0895 code
Considering that the P0895 code can be triggered by several different causes, a careful and methodical diagnosis is necessary. Be sure to consider any related codes which may be stored with the P0895 code.
Need help with a P0895 code?
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