P0857 OBD-II Trouble Code: Traction Control Input Signal Range/Performance

P0857 code definition

The P0857 refers to a malfunction found in the vehicle's traction control input signal circuit. This error is most often registered by the Powertrain Control Module (PCM), but it may also be detected by one of the other control modules relating to the traction circuit.

What the P0857 code means

The traction control input signal circuit relays information to system-related control modules, promoting cooperation between the vehicle's traction and engine performance. This trouble code occurs when one of the control modules has failed to receive a message from the traction control input signal circuit.

What causes the P0857 code?

The P0857 will be logged when the PCM or one of the other control modules fails to pick up an input signal from the traction control module. In many cases, this is a result of liquid contact damage with the module or one of the related components. In the vast majority of cases, the P0857 is the result of a faulty traction control switch. The traction control module may be defective. Defective, broken, corroded or disconnected wiring may also cause a P0857 code.

What are the symptoms of the P0857 code?

A failure of the traction system and problems with transmission are the typical symptoms associated with a P0857. Fuel efficiency is generally weakened as well. At its worst, the P0857 will disable the vehicle's ability to shift gears. For the purpose of diagnosing the code, the P0857 code will be stored in the vehicle's onboard computer and the dashboard engine light illuminated.

How does a mechanic diagnose the P0857 code?

The P0857 code can initially be identified by inputting an OBD-II code reader into the vehicle's computer. The traction control switches should be inspected first, as these are by and large the most common sources of a P0857 trouble code. If the problem is suspected to lie in one of the traction-related control modules, a specialized scanner like the Autohex may spare you the time of inspecting them all individually. All wiring related to the traction control circuit should be inspected for signs of corrosion and disconnection. Any other components related to the traction circuit should be looked over as well.

Common mistakes when diagnosing the P0857 code

The traction control module is sometimes blamed as the cause mistakenly. However, the problem more often lies with malfunctioning switches, circuits and/or wiring.

How serious is the P0857 code?

The severity of a P0857 code should be determined by its symptoms. Mild cases will affect drivability, while more advanced instances will result in the vehicle's inability to shift gears, rendering it inoperable. Because reduced drivability can pose a safety concern on the road, the P0857 code should be dealt with as soon as possible.

What repairs can fix the P0857 code?

• If a traction control switch has been proven to be faulty or damaged, it should be replaced

• Corroded, faulty, damaged and disconnected wiring should be solved as necessary

• If the control modules themselves are being repaired, you should attach the module in question with a memory saver in order to spare yourself costly reprogramming

• Any voltage readings should be compared alongside the manufacturer's default specifications in order to potential a potential issue

• The vehicle should be test driven following repairs to ensure that the trouble code has been dealt with successfully

Additional comments for consideration regarding the P0857 code

The P0857 trouble code only pertains to vehicles with electronic traction control systems.

Need help with a P0857 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.