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 Volkswagen, Porsche, Honda, Audi, Acura, etc. Although generic, the exact repair steps may vary depending on the year, make, model, and powertrain configuration.
If your vehicle has stored a P081E code, it means that the Powertrain Control Module (PCM) has received an input data signal from the input and output speed sensors indicating that the clutch is slipping excessively. The B designation clutch indicates that the vehicle is equipped with a Clutch Pedal Position Sensor (CPPS) that operates similarly to a Throttle Position Sensor (TPS).
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 various engine and transmission sensors to calculate the maximum allowable transmission (clutch) slip degree. Wear on the clutch disc and pressure plate, as well as mechanical failure, can lead to excessive clutch slippage. CPPS voltage deviations can also cause a P081E to be stored. The PCM uses voltage input signals from the transmission input speed sensor and transmission output speed sensor, along with the clutch pedal position, to determine if the clutch is operating within the parameters for maximum allowable slip.
Often, when the friction material on the clutch disc wears below a certain level, the clutch begins to slip. This condition is typically accompanied by the distinct smell of burnt friction material.
If the PCM detects a degree of transmission (clutch) slip that exceeds the maximum allowable parameters, a P081E code may be stored and a Malfunction Indicator Lamp (MIL) illuminated. Several ignition cycles (with a failure) may be required for the MIL to light up.
How Severe Is This DTC?
A stored P081E code indicates that a serious electrical issue or clutch failure has occurred. In any case, 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 P081E trouble code may include:
Transmission slipping
Hard gear engagement
Clutch engagement occurs near the top
Strong smell of burnt friction material
What Are Some of the Common Causes of the Code?
Causes
of this code may include:
Faulty CPPS sensor
Worn clutch disc and/or pressure plate
Defective input or output speed sensor
Shorted wiring for input/output speed sensors
Faulty PCM or programming error
What Are the P081E Troubleshooting Steps?
Before attempting to diagnose a P081E, ensure that the clutch, pressure plate, and release bearing are functioning correctly. You will also want to check the clutch arms and linkages, as well as the clutch hydraulic system, if applicable.
A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle-specific diagnostic information will be necessary to diagnose a P081E code. An oscilloscope may also be helpful when attempting to diagnose input and output speed sensor malfunctions. The CPPS output voltage can also be monitored using the DVOM or oscilloscope. The latter is more effective for detecting voltage spikes and glitches.
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 engine size, stored codes, and presented symptoms. If you find one, it may provide useful diagnostic information.
With the clutch functioning properly, 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 note 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 immediately resets, 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, ground, and signal at the transmission input and output speed sensors (key on, engine off). The input and output speed sensor circuits typically consist of a reference voltage, a signal wire, and a ground.
Step 4
Use the oscilloscope (connected to the signal circuit and ground) to check for spikes and glitches in the CPPS signal range.
Most B clutch slip codes can be attributed to a CPPS failure