P0811 Excessive Clutch Slippage

Description and meaning of DTC p0811

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Audi, Volkswagen, Volvo, BMW, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration. If your vehicle has stored a code P0811, it means that the powertrain control module (PCM) has received a data input signal from the input and output speed sensors which indicates that the clutch is slipping excessively. The transmission control module (TCM) may be a stand alone unit but is most commonly integrated into a single housing with the engine control module (ECM). This is called the PCM. The PCM utilizes input signals from multiple engine and transmission sensors to calculate the maximum allowable degree of transmission (clutch) slippage. Clutch disc and pressure plate wear, as well as mechanical failure, may lead to excessive clutch slippage. The PCM uses voltage input signals from the transmission input speed sensor and transmission output speed sensor to determine if the clutch is functioning within the parameters for maximum allowable slippage. As with many other transmission malfunctions, a clutch slippage code may be caused by electrical or mechanical failure. Often when the friction material on the clutch disc is worn down below a certain level, the clutch begins to slip. This condition is usually accompanied by the distinctive odor of burnt friction material. If the PCM detects a degree of transmission (clutch) slippage that exceeds maximum allowable parameters, a code P0811 may be stored and a malfunction indicator lamp (MIL) illuminated. Multiple ignition cycles (with a failure) may be required for MIL illumination.

p0811 diagnostic trouble code symptoms

Symptoms of a P0811 trouble code may include:Transmission slippageHarsh gear engagementClutch engagement occurs near the topStrong odor of burnt friction material

DTC p0811 - possible causes

Causes for this code may include:Worn clutch disc and/or pressure plateDefective input or output speed sensorShorted wiring for input speed/output speed sensorsFaulty PCM or a programming error

How to fix OBD-II diagnostic trouble code p0811

Before attempting to diagnose a P0811, make sure that the clutch, pressure plate, and throwout bearing are functioning properly. You will also want to check clutch arms and bushings as well as clutch hydraulics if applicable. A diagnostic scanner, a digital volt/ohmmeter (DVOM), and a source of vehicle specific diagnostic information will be required to diagnose a code P0811. An oscilloscope may also be helpful when attempting to diagnose input and output speed sensor malfunctions. You may use your source of vehicle information to locate a technical service bulletin (TSB) that matches the vehicle year, make, and model as well as the engine size, code/s stored, and symptoms exhibited. If you find one, it could yield helpful diagnostic information. With the clutch functioning properly, proceed with the first step of the diagnosis. Step 1Use the scanner (connected to the vehicle diagnostic connector) to retrieve all stored codes and pertinent freeze frame data. It is a good idea to write this information down before clearing the codes then test-drive the vehicle until the PCM either enters readiness mode or the code is reset. If the PCM enters readiness mode at this time, the code is intermittent and may be much more difficult to diagnose. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made. Step 2If the code is immediately reset, the next step of your diagnosis will require that you search your vehicle information source for diagnostic flow-charts, connector pin-out charts, connector face views, and component testing procedures/specifications. Step 3Use the DVOM to test voltage, ground, and signal at the transmission input and output speed sensors (key on and engine off). Input and output speed sensor circuits typically consist of a reference voltage, a signal wire, and a ground. Step 4Use the oscilloscope (connected to the signal circuit and ground) to check for spikes and glitches in the speed sensor signal pattern. Most transmission slippage codes are caused by excessively worn clutch components

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