DTC P0851

DTC P0851  : Neutral Position Sensor A Circuit Low Voltage

NOTE:  Before you troubleshoot, review the general troubleshooting information .

DTC (PGM-FI)

1. Problem verification

   -1. Turn the vehicle to the ON mode.

   -2. Clear the DTC with the HDS.

   -3. Check for Pending or Confirmed DTCs with the HDS.

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   P0851 Neutral Position Sensor A Circuit Low Voltage

   Is DTC P0851 indicated?

   YES 

   The failure is duplicated. Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the neutral position sensor and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot .

2. DTC check

   -1. Check for Pending or Confirmed DTCs with the HDS.

   DTC Description	Confirmed DTC	Pending DTC	Freeze Frame
   P0851 Neutral Position Sensor A Circuit Low Voltage
   P1707 Neutral Position Sensor B Circuit Low Voltage

   Are DTC P0851 and P1707 indicated at the same time?

   YES 

   Go to step 3.

   NO 

   Go to step 5.

3. Determine possible failure area (neutral position sensor, others)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the following connector.

   Neutral position sensor 4P connector

   -3. Turn the vehicle to the ON mode.

   -4. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Neutral position sensor 4P connector: disconnected
   Test point 1	Neutral position sensor 4P connector No. 1
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there about 5 V?

   YES 

   Replace the neutral position sensor .

   NO 

   Go to step 4.

4. Open wire check (VCC2 line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Jump the SCS line with the HDS.

   -3. Disconnect the following connector.

   PCM connector B (51P)

   -4. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Neutral position sensor 4P connector: disconnected
   	PCM connector B (51P): disconnected
   Test point 1	PCM connector B (51P) No. 29
   Test point 2	Neutral position sensor 4P connector No. 1

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The VCC2 wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P0851 goes away and the PCM was updated, troubleshooting is complete. If DTC P0851 goes away and the PCM was substituted, replace the original PCM .

   NO 

   Repair an open in the VCC2 wire between the PCM (B29) and the neutral position sensor.

5. Determine possible failure area (neutral position sensor, others)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the following connector.

   Neutral position sensor 4P connector

   -3. Connect terminals A and B with a jumper wire.

   Terminal A	Neutral position sensor 4P connector No. 1
   Terminal B	Neutral position sensor 4P connector No. 3

   Courtesy of HONDA, U.S.A., INC.

   -4. Turn the vehicle to the ON mode.

   -5. Check the parameter (s) below with the HDS.

   Signal	Current conditions
   	Values	Unit
   NEUTRAL POSITION SENSOR 1

   Is about 5 V indicated?

   YES 

   Replace the neutral position sensor .

   NO 

   Go to step 6.

6. Open wire check (NSS1 line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Jump the SCS line with the HDS.

   -3. Disconnect the following connector.

   PCM connector B (51P)

   -4. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Neutral position sensor 4P connector: disconnected
   	PCM connector B (51P): disconnected
   Test point 1	PCM connector B (51P) No. 33
   Test point 2	Neutral position sensor 4P connector No. 3

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The NSS1 wire is not open. Go to step 7.

   NO 

   Repair an open in the NSS1 wire between the PCM (B33) and the neutral position sensor.

7. Shorted wire check (NSS1 wire)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	PCM connector B (51P): disconnected
   	Neutral position sensor 4P connector: disconnected
   Test point 1	Neutral position sensor 4P connector No. 3
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair a short in the NSS1 wire between the PCM (B33) and the neutral position sensor.

   NO 

   The NS1 wire is OK. Update the PCM if it does not have the latest software, or substitute a known-good PCM , then recheck. If DTC P0851 goes away and the PCM was updated, troubleshooting is complete. If DTC P0851 goes away and the PCM was substituted, replace the original PCM .