Traction Control Input Signal High
The P0859 code means the vehicle's onboard diagnostic system has detected: Traction Control Input Signal High. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $100 - $500 (usually wiring or the feeding sensor - diagnose before parts)
Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.
Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.
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Common Symptoms
- Check Engine Light on
- Harsh or altered shifting as the TCM falls back to defaults
- Related input reading implausible on a scan tool
Probable Causes (Ranked by Likelihood)
- Damaged wiring or corroded connector in the signal circuit High
- Failed sensor or module feeding the signal High
- TCM input circuit fault Low
Frequently Asked Questions
What does P0859 mean?
P0859 means the Traction Control Input is out of expected range - the transmission control module cannot trust this input.
Can I keep driving with P0859?
Usually yes, but shift quality may suffer and the TCM is running on defaults. Have it diagnosed soon.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Read the live value of the affected input on a scan tool and compare against expected range.
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Inspect wiring and connectors for the circuit.
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Follow the OEM pinpoint test for the specific input.
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Clear codes and road-test to confirm.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- 2010-2020 Toyota Camry
- 2012-2019 Honda Civic
- 2008-2018 Ford F-150
- 2011-2020 Chevrolet Silverado
Related Codes
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