What is Code P0850 and How to Diagnose the Problem in Your Car

Code P0850 refers to a fault in the input circuit that provides the powertrain control module (PCM) with information about the position of the parking switch. This error manifests as an abnormal voltage reading, indicating an issue with the switch, its wiring, or the PCM itself. In this article, we will detail the causes of this code, the signs your vehicle may show, and what to do to resolve it.

What is Fault Code P0850?

The Engine Control Module (ECM) continuously monitors the parking switch, verifying that its electrical signal matches predefined values. If this signal deviates from expected parameters, the ECM logs a fault and stores the diagnostic trouble code P0850 in the vehicle's memory.

Signs That Fault Code P0850 Has Been Triggered

The check engine light activates, and the cruise control system may be disabled as a safety measure.

Abrupt gear changes or the inability to shift gears may indicate a P0850 code. The brake light switch interacts with the transmission control system, and a malfunction here can generate incorrect signals to the control module, resulting in abrupt or failed gear shifts.

Additionally, reduced fuel efficiency may be a related symptom, as a malfunctioning switch can affect the engine management strategy.

In Which Cars Is Fault Code P0850 Common?

Although code P0850 occurs more frequently in models like the Toyota Camry, Honda Civic, Nissan Sentra, Hyundai Elantra, and Ford Focus, it is important to remember that it can affect a wide range of vehicles. We always recommend consulting your owner's manual or a specialized mechanic for an accurate diagnosis.

How to Determine If Your Vehicle's Problems Are Due to Fault Code P0850

To diagnose code P0850, a technician should start by performing a code scan with an OBD-II scanner. Next, a thorough visual inspection of the parking switch circuit, including its wiring and connectors, will be conducted. If damage is detected, repairs or replacements will be performed. Finally, the fault code will be cleared from the PCM, and a test drive will be conducted to verify the effectiveness of the repairs.

What Causes Fault Code P0850?

The P0850 OBDII code may be triggered by:

• Corrosion: Excessive corrosion in the parking switch increases electrical resistance in the circuit.
• Misalignment: Misalignment of the switch can cause an incorrect electrical signal.
• Defect: The parking switch may have an internal fault that prevents it from functioning properly.

Solutions for Resolving Fault Code P0850

To resolve code P0850, a mechanic may:

• Adjust the sensor: Check and adjust the position of the sensor indicating the car's gear.
• Replace the switch: Replace the component that detects whether the car is in park or neutral.

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