What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). This may include, but is not limited to, vehicles from Mercedes Benz, Toyota, Kia, Mitsubishi, Jeep, Chevrolet, Dodge, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
If your vehicle has stored a P0893 code, it means that the Powertrain Control Module (PCM) has received a data input signal indicating that multiple automatic transmission gears have been engaged simultaneously.
The Transmission Control Module (TCM) may be a standalone unit but is most often integrated into a single housing with the Engine Control Module (ECM). This is referred to as the PCM.
The PCM uses input signals from multiple engine and transmission sensors to calculate the automatic shift strategy. Electronic shift solenoids are used to interrupt the flow of high-pressure fluid so that the transmission can shift gears. If multiple solenoids are activated simultaneously, multiple gears will be engaged, and the desired gear ratio will be impossible to achieve.
As with many other automatic transmission malfunctions, the engagement of multiple gears can also be caused by mechanical failure. Often, when the friction material on one or more clutch discs is compromised, the hot material effectively “welds” several clutches together and creates a condition of multiple gear engagement. This condition is accompanied by the distinctive smell of burnt friction material in the fluid.
If the PCM detects that multiple automatic transmission gears are engaged simultaneously, a P0893 code may be stored and a Malfunction Indicator Lamp (MIL) illuminated.
How severe is this DTC?
A stored P0893 code indicates that a serious electrical problem or a catastrophic mechanical failure has occurred. The conditions that contributed to the storage of a code of this nature should be rectified as soon as possible.
What are some of the symptoms of the code?
Symptoms of a P0893 trouble code may include:
- Transmission slipping
- Delayed and/or harsh gear engagement
- Irregular transmission shifting patterns
- Strong smell of burnt friction material in the transmission fluid
What are some of the common causes of the code?
Causes
of this code may include:
- Catastrophic internal (mechanical) transmission failure
- Shorted wiring for the shift solenoids
- Faulty shift solenoid(s)
- Faulty PCM or programming error
What are the troubleshooting steps for P0893?
When diagnosing automatic transmission codes, you should start by ensuring that the transmission fluid is clean and that the transmission is filled to the appropriate level. If the fluid level is low, locate the source of the leak and repair the condition. Refill the transmission with the recommended fluid and proceed.
If the fluid is excessively dark and has a strong smell of burnt friction material, it will need to be replaced. To do this, remove the transmission pan (and drain the torque converter) or flush the transmission (recommended). In either case, you will also want to replace the filter at this time. When removing the transmission pan, be sure to save any debris that may have landed in it. If the pan is relatively free of debris, you can assume the clutches are mechanically intact. If there is an excessive amount of friction material in the pan (and stuck to the magnet), the transmission will require rebuilding by a qualified technician.
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be required to diagnose a P0893 code.
If you can use your vehicle information source to locate a Technical Service Bulletin (TSB) that matches the vehicle’s year, make, and model; as well as the engine size, stored code(s), and presented symptoms, it could provide useful diagnostic information.
With the transmission filled to the appropriate level with the recommended fluid, proceed to the first step of diagnosis.
Step 1
Use the scanner (connected to the vehicle’s diagnostic connector) to retrieve all stored codes and relevant freeze frame data. It is a good idea to record this information before clearing the codes, then test drive the vehicle until the PCM enters readiness mode or the code resets.
If the PCM enters readiness mode at this point, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
Step 2
If the code resets immediately, the next step in your diagnosis will require you to search your vehicle information source for diagnostic flowcharts, connector pinout diagrams, connector face views, and component testing procedures/specifications.
Step 3
Use the DVOM to test the voltage at the shift solenoids (key on, engine off). Shift solenoid circuits typically consist of a constant voltage supply and a ground provided by the PCM at the appropriate time to achieve the desired gear ratio.
Most multiple gear engagement codes are caused by catastrophic mechanical transmission failure