P0856 OBD-II Trouble Code: Traction Control Input Signal

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0856 code

P0856 is a diagnostic trouble code (DTC) for "Traction Control Input Signal". 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 diagnostic. 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.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0856 DIAGNOSTIC Get a fair and transparent estimate upfront

P0856 code definition

The P0856 trouble code detects an issue with the traction control input signal.

What the P0856 code means

The P0856 code is a standard OBD-II trouble code that notes a problem with the traction control input signal. The traction control input signal is responsible for sending data to the powertrain control module (PCM), and other control modules. The PCM and the other control modules use this data to determine the proper revolutions per minute (RPM) for the vehicle, as well as engine timing, fuel delivery, and many other factors. When the PCM and accompanying control modules do not get input signals from the traction control module, then the P0856 trouble code will be triggered.

What causes the P0856 code?

The P0856 trouble code is usually caused by a faulty ON/OFF switch in the traction control system. This usually is the result of spills or leakage damaging the control switch, or faulty, loose, or damaged wires, connectors, and other electrical components in the system. In addition to a defective switch, corrosion on the traction control sensor connector can cause the P0856 code to be detected. While it is rare, the traction control module may also be defective.

What are the symptoms of the P0856 code?

When the P0856 trouble code is detected, the check engine soon warning light will illuminate on the instrument cluster, and the traction control malfunction warning light will likely illuminate as well. In addition to these warnings, the traction control system is likely to stop working, which can result in a loss of grip (mainly on slippery or icy conditions). The transmission may also have a hard time shifting, or may not shift at all (and may enter limp-in mode), and the vehicle will likely experience reduced fuel economy.

How does a mechanic diagnose the P0856 code?

The P0856 code should be diagnosed using a standard OBD-II trouble code scanner. A trained mechanic will use the scanner to view the freeze frame data, and assess the code. The mechanic will also look for the presence of additional trouble codes. The codes should then be reset, and the vehicle should be restarted, to see if the code persists. If the code does not return, then it was likely triggered erroneously, or represents an intermittent issue.

If the P0856 trouble code returns, the mechanic should visually inspect the electrical components in the traction control system, to see if there are any loose, damaged, or corroded wires and connectors. All damaged components should be replaced. If the technician notices that the ON/OFF switch is damaged as well, it should be replaced.

Every time a component is replaced, the codes should be reset and the vehicle restarted before the mechanic proceeds. This will allow the mechanic to tell whether the issue has been resolved, or if there is more work to do.

Common mistakes when diagnosing the P0856 code

The most common mistake made when diagnosing the P0856 code is the failure to adhere to the OBD-II trouble code diagnosis protocol. All mechanics should follow the protocol properly, to ensure that both the diagnosis and the repair is not only properly done, but efficient as well.

It is common for the traction control module to be replaced when the only issue was a faulty ON/OFF switch or some damaged electrical components.

How serious is the P0856 code?

A vehicle with the P0856 trouble code present is still drivable. However, the vehicle’s traction control system will likely be disabled, meaning the car will not have good traction on wet or icy roads. Furthermore, unnecessary stress may be placed on the transmission, which can ultimately cause damage. Even though the car may be drivable, the P0856 code should be inspected and resolved as quickly as possible.

What repairs can fix the P0856 code?

Some possible repairs for the P0856 trouble code include:

Additional comments for consideration regarding the P0856 code

The P0856 trouble code only applies to cars that have electronic traction control systems.

Need help with a P0856 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.

trouble codes
OBD-II
P0856

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0856 code.

SCHEDULE P0856 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,626

Rating Summary
5,199
206
50
34
137
5,199
206
50
34
137

Robert

11 years of experience
104 reviews
Robert
11 years of experience
Nissan Quest - Check Engine Light is on - Alexandria, Virginia
Punctual. Knowledgeable. Professional. Empathic, went the extra mile to explain in lay words the mechanical jargon. Excellent manners and customer service oriented. Client’s best interest and safety was always his top priority. From now on your company has in me a client for life. Thanks Robert!!!! 

Chris

21 years of experience
1861 reviews
Chris
21 years of experience
Mercedes-Benz E320 - Check Engine Light is on - Ladera Ranch, California
Chris was friendly, professional and knowledgeable. He got to the point of my concerns, explained what he was finding on his system and gave me his recommendations. I fully appreciate him taking the time to explain everything and a bit of history on my vehicle. Thanks again Chris.

Michael

15 years of experience
574 reviews
Michael
15 years of experience
Hyundai Accent - Check Engine Light is on - Marietta, Georgia
I had a great experience with Michael. He's extremely professional, friendly, and understands his craft. Highly recommended.

Chris

15 years of experience
274 reviews
Chris
15 years of experience
Dodge Durango - Check Engine Light is on - San Diego, California
Showed up early, was a friendly dude, kept me informed via text, did clean work and finished early. Would hire again.


More related articles

P0286 OBD-II Trouble Code: Cylinder 9 Injector Circuit High
P0286 P0286 code definition When the P0286 code gets stored, it’s because the vehicle’s ECM has received a voltage reading from the fuel injector circuit that isn’t within the parameters designated by the manufacturer. The reading could have also come...
P0023 OBD-II Trouble Code: Camshaft Position B - Actuator Circuit (Bank 2)
P0023 P0023 code definition Camshaft Position B - Actuator Circuit (Bank 2) What the P0023 code means P0023 is the OBD-II generic code indicating the Engine Control Module (ECM) has determined that the bank 2 exhaust camshaft Oil Control Valve...
P2295 OBD-II Trouble Code: Fuel Pressure Regulator 2 Control Circuit Low
P2295 P2295 code definition Fuel pressure regulator 2 control circuit low What the P2295 code means This trouble code indicates that the powertrain control module has detected a low reference voltage from the fuel pressure regulator circuit. What are the...

Related questions

Transmission doesn't shift, gets stuck in fail safe mode.

Depending on the circumstances, it may in fact be in "fail-safe" mode. When this happens you will normally also have a Check Engine Light on which will usually cause fault codes to be registered in the ECU. When the vehicle...

My van was missing and rough idling then I turned it off one day and the next day it starts then dies and some times it won't start

Hello, thanks for writing in about your 2001 Dodge Caravan. For certain, given your mileage and codes for these 2 components, replacing these 2 sensors is the minimum. Cleaning the idle air control valve, throttle body, and PCV valve should...

I'm having problems with code po740

Hi there. In order to be able to give you more exact information I would need to know whether or not the vehicle is equipped with the CVT transmission. It sounds like you have the regular transmission in your vehicle....

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com