What Does C1859 Mean?
The PRNDL (Park, Reverse, Neutral, Drive, Low) input circuit #2 has failed, meaning the transmission range sensor or inhibitor switch is not properly communicating the selected gear position to the control module. This is one of multiple digital inputs used to determine the gear selector position. The driver may notice the gear indicator displaying incorrectly, inability to shift, or the vehicle starting in a failsafe gear.
Common Causes
35%
Faulty transmission range sensor (TRS) or inhibitor switch with worn internal contacts on the #2 circuit
25%
Wiring harness fault between the transmission range sensor and the control module, including open or shorted conductors
20%
Corroded or damaged connector at the transmission range sensor caused by fluid leakage or road spray exposure
12%
Shift linkage misadjustment causing the range sensor to be out of calibration with the actual selector position
8%
Transmission control module internal fault on the PRNDL input #2 processing circuit
Diagnostic Steps
1
Monitor all PRNDL input states (Input #1 through #4) on the scan tool while slowly moving the gear selector through each position. Document which inputs toggle and compare to the expected binary pattern in the service manual.
2
Inspect the transmission range sensor connector for ATF contamination, corrosion, or bent pins. Clean and reseat the connector, then retest.
3
Back-probe the PRNDL #2 circuit at both the sensor and module connectors. Verify continuity through all gear positions and check for proper voltage switching (typically ground or 12V logic depending on design).
4
Verify shift cable adjustment by confirming the manual valve lever detent positions align with the gear selector positions. Readjust if the sensor is not centered in each detent.
5
If the sensor is a contact-type switch, measure resistance across the #2 input terminals in each gear position and compare to the manufacturer's resistance chart.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The PRNDL (Park, Reverse, Neutral, Drive, Low) input circuit #2 has failed, meaning the transmission range sensor or inhibitor switch is not properly communicating the selected gear position to the control module. This is one of multiple digital inputs used to determine the gear selector position. T...
The most common cause of C1859 (PRNDL Input #2 Circuit Failure) is: Faulty transmission range sensor (TRS) or inhibitor switch with worn internal contacts on the #2 circuit
Typical repair costs for C1859 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle may default to a single gear or fail to recognize the selected gear range, leading to unexpected behavior when shifting. Reverse lights and starter inhibit functions may be affected. The vehicle can typically be driven cautiously in limp mode, but have it diagnosed promptly to avoid being stranded or encountering unsafe shifting behavior.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1859 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Chassis
System
Transmission / Gear Selection
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
