Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0851
DTC P0851:Â Neutral Position Sensor A Circuit Low Voltage
General DescriptionÂ
Table A: Neutral position sensor output voltageÂ
| Â | NSS1 voltage | NSS2 voltage |
|---|---|---|
| Neutral | 2.7 - 3.0 V | 1.35 - 1.5 V |
Neutral position sensor A and neutral position sensor B are semiconductor type that output different voltage characteristics. Each neutral position sensor output voltage which depends on the condition is shown in Table A. The powertrain control module (PCM) judges whether it is in neutral or not from the neutral position sensor output voltage, and uses the information for auto idle stop system control and other controls. Neutral position sensor A is for judging the neutral, and the sensors compare their output voltage to each other for malfunction detection. When the neutral position sensor A output voltage is a specified voltage for a set time, the PCM detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC TypeÂ
| Execution | Continuous |
| Sequence | None |
| Duration | 2.0 seconds or more |
| DTC Type | One drive cycle, MIL off |
Enable ConditionsÂ
| Condition | Minimum | Maximum |
|---|---|---|
| 12 volt battery voltage [BATTERY] | 10.0 V | - |
| Vehicle | ON mode | |
[ ]: HDS Parameter
Malfunction ThresholdÂ
The neutral position sensor A output voltage [NEUTRAL POSITION SENSOR 1] is 0.15 V or less for at least 2.0 seconds.
Possible CauseÂ
NOTE:Â The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Neutral position sensor A VCC line open
- Neutral position sensor A NSS1 line short to ground
- Neutral position sensor A failure
- PCM internal circuit failure
Diagnosis DetailsÂ
Conditions for setting the DTCÂ
When a malfunction is detected, a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory. The MIL does not come on.
Conditions for clearing the DTCÂ
The Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.