P086E

What it means

P086E means the control unit has seen the signal from neutral position sensor 'A' drop out, jump about or give readings that don't make sense. The sensor signals when the gearbox is in neutral, and the control unit uses it for starting permission, stop/start, idle control and other functions. The fault is set when the signal is intermittent or erratic rather than permanently failed. Where the sensor is fitted and how it works depends on the vehicle and gearbox type.

Symptoms

• Engine intermittently refuses to crank or start, or starts only with the selector or clutch moved
• Stop/start system not working or behaving inconsistently
• Gear position display or neutral indicator flickering or showing the wrong gear
• Idle speed hunting or the engine stalling when coming to a stop
• Cruise control or other driver aids cutting out
• Warning light on, with possible reduced performance or limp mode on some models

Possible causes

• Damaged, corroded or loose wiring or connector at the neutral position sensorlikely
• Worn or faulty neutral position sensor or switch, including internal contact wearlikely
• Sensor or linkage out of adjustment, or selector mechanism worn so the sensor sees an unstable positionpossible
• Oil leak contaminating the sensor or connector, or fluid ingress into the sensorpossible
• Low or unstable supply voltage or poor earth affecting the sensor circuitpossible
• Fault in the engine or transmission control unit, or a software issuerare

How to diagnose

1. Read all stored and pending codes and note freeze frame data, including when the fault set and what gear or selector position was reported
2. Check for other related codes such as other gear position, clutch switch or supply voltage faults, and for any technical service information for the model
3. Visually inspect the sensor, wiring and connector for chafing, corrosion, oil contamination, heat damage or a loose fit
4. With a scan tool, watch the neutral position or gear status live while moving the selector or gear lever and wiggling the harness, looking for dropouts
5. Check the sensor supply, signal and earth with a multimeter against the manufacturer's data, including voltage drop under load
6. Check the battery condition and charging voltage, as low voltage can cause erratic sensor readings
7. Inspect the selector linkage or cable and sensor mounting for wear or misadjustment, following the model's procedure
8. Test the sensor itself against specification and, if all else is sound, consider a control unit fault only after wiring and sensor are proved good

How to fix

• Repair or replace damaged wiring and clean or renew corroded or contaminated connectors
• Replace the neutral position sensor or switch if it fails testing, and adjust or calibrate it as the manufacturer specifies
• Adjust or repair the selector linkage or cable, or the sensor mounting, if it is worn or out of position
• Fix any oil leak that is contaminating the sensor or connector, then clean or replace the affected parts
• Correct battery, charging or earth faults that are disturbing the sensor signal
• Update or reprogram the control unit only if the manufacturer lists a software fault as a known cause, or replace it once proven faulty

Can I keep driving?

Nearby codes

• P086DGenericNeutral Position Sensor A Circuit High
• P086FGenericNeutral Position Sensor A Not Learned