P2938 Mercedes-Benz Auto Trouble Code

P2938 Mercedes-Benz OBD2 reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.

The leak detection pump is part of the evaporative emissions system. This system tests the fuel system to make sure it is not leaking fuel vapors into the air. The system pulls a vacuum on the fuel system and holds it for a period of time.

P2938 Mercedes-Benz Possible Solution:

Vehicle Speed Sensor (VSS) Out of Self Test Range Indicates the VSS input signal is out of Self Test range. If the PCM detects a VSS input signal any time during Self Test, a DTC P1501 will be set and the test will abort. Noisy VSS input signal from Radio Frequency Interference/ Electro-Magnetic Interference (RFI/EMI) external sources such as ignition wires, charging circuit or after market equipment. Check for VSS input to be 0 mph when vehicle transmission is in Park.

P2938 Mercedes-Benz Description For All Models :

P2938 Mercedes-Benz Trouble Repair :

OBD 2 P2938 Mercedes-Benz code and tailpipe testing are two different approaches to identify vehicles in need of repair. The OBD system looks for broken or malfunctioning emissions control components while tailpipe tests sample a vehicle's exhaust to see if it is above or below certain prescribed limits. Given the robust nature of today's emissions control components, it is entirely possible for an individual component to malfunction without leading to an immediate increase in emissions at the tailpipe. In such cases, other components (like the catalyst) can temporarily compensate for the part that is broken however, these other components can only do double duty for so long before they, too, begin to malfunction. Because of its ability to monitor individual components, OBD is able to give motorists an early warning that repairs are needed; it is because of this early warning capability that OBD will sometimes fail vehicles that would otherwise pass a tailpipe test.

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