P0859 OBD-II Trouble Code: Traction Control Input Signal High

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Cost of diagnosing the P0859 code

P0859 is a diagnostic trouble code (DTC) for "Traction Control Input Signal High". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light is on diagnostic inspection. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

P0859 code definition

A P0859 trouble code indicates that the vehicle's Powertrain Control Module (PCM) has reported a malfunction relating to the traction control input signal circuit.

What the P0859 code means

The traction control system regulates several aspects of the vehicle's drive system, particularly with regards to engine power and fuel delivery. A P0859 trouble code will be logged on the vehicle's computer if the PCM fails to receive a signal from the traction control system.

What causes the P0859 code?

  • In the vast majority of cases, the P0859 code is caused by a defective traction control switch. The switch itself may be faulty or damaged. Technicians report defective switches in this code instance are often damaged due to liquid contact.

  • Shorted, corroded and damaged wires may also be to blame for a P0859 signal malfunction. Moreover, technicians have cited a corroded sensor connector as a common reason for this trouble code.

What are the symptoms of the P0859 code?

The reported symptoms of a P0859 code vary from purely traction-related concerns to a failure of the transmission system. Traction problems are most commonly reported, particularly if a P0859 code-afflicted car is driven on slippery surfaces. Harsh or failed shifting may also come alongside a P0859 code. The P0859 trouble code and dashboard trouble indicator will both be activated for the sake of highlighting and diagnosing the concern.

How does a mechanic diagnose the P0859 code?

A technician may first diagnose the P0859 code by reading it via an OBD-II code reader. Components related to the traction system (particularly the traction control system's activation switch) should be inspected and tested for signs of fault or malfunction. All wires relating to the traction control system should be inspected thoroughly in order to verify any potential signs of corrosion, damage, wear or disconnection. In the case that there is a possible issue with one of the vehicle's control modules, a specialized scanner (such as an Autohex) may be used in order to pinpoint the source of the problem.

Common mistakes when diagnosing the P0859 code

Although a faulty traction control module is sometimes to blame for a P0859 code, it is often mistakenly replaced when the real problem lies with broken electrical circuitry or a faulty switch.

How serious is the P0859 code?

A P0859 trouble code can result in drivability issues for the vehicle. Particularly if the vehicle's typical driving surfaces are slippery, a P0859 code can make the vehicle more dangerous to drive. In addition, an unpredictable transmission system resulting from a P0859 can make driving the vehicle a precarious situation.

What repairs can fix the P0859 code?

Additional comments for consideration regarding the P0859 code

The P0859 trouble code only applies to vehicles with electronic traction control systems. Due to the high amount of circuitry associated with this code and the traction system, it is recommended that these repairs be left to a proper technical specialist.

Need help with a P0859 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.

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P0859

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Nazareth

26 years of experience
168 reviews
Nazareth
26 years of experience
Mercedes-Benz CLA250 - Check Engine Light is on - Los Angeles, California
Polite and very professional! Nazareth quickly identified my car was suffering from low voltage issues and the battery was the problem. The reader was showing 8 volts hence why my car didn’t receive enough power to start, it needed 12v. My battery was 4 years old and never been changed. Thank you Nazareth!

Cornelius

17 years of experience
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Cornelius
17 years of experience
Chevrolet Cobalt - Check Engine Light is on - Peachtree City, Georgia
He was very helpful with explaining what could lead to my check engine light being on. And helping clear my engine light.

Marco

28 years of experience
78 reviews
Marco
28 years of experience
Nissan Maxima - Check Engine Light is on - Highland, California
Marco did a great job of finding the source of the problem and his recommendations were greatly appreciated.

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8 years of experience
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Juan
8 years of experience
Chevrolet Tahoe - Check Engine Light is on - Altamonte Springs, Florida
Juan was on time for both appointments. He was knowledgeable and polite and I will most definitely be requesting him for my next steps based on the quote he provided me for other issues I need to address. Excellent customer service and top notch repair work!


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