DTC P0651 (PGM-FI System (1.5 L Engine))

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DTC P0651: Sensor Reference Voltage B Malfunction

General Description

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

The powertrain control module (PCM) is equipped with a voltage monitor (5 V power source) to supply a stable 5 V to each sensor as reference voltage. The correct voltage for the sensors are loaded in the CPU of the PCM (A/D input) and when the sensor power voltage is a set value (high or low) for a certain time, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type

Execution	Continuous
Sequence	None
Duration	2.0 seconds or more
DTC Type	One drive cycle, MIL on

Enable Conditions

Condition
Vehicle	ON mode

Malfunction Threshold

The sensor power voltage is 6.00 V or more, or 3.99 V or less, for at least 2.0 seconds.

Possible Cause

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

A/C pressure sensor VCC line short to power
Accelerator pedal position (APP) sensor VCC line short to power
Turbocharger VCC line short to power
Turbocharger boost sensor VCC line short to power
Camshaft position (CMP) sensor A VCC line short to power
Mass airflow (MAF) sensor/intake air temperature (IAT) sensor 1 VCC line short to power
Engine oil pressure sensor VCC line short to power
Rocker arm oil pressure sensor VCC line short to power
Fuel tank pressure (FTP) sensor VCC line short to power* 1
A/C pressure sensor VCC line short to ground
APP sensor VCC line short to ground
Turbocharger VCC line short to ground
Turbocharger boost sensor VCC line short to ground
CMP sensor A VCC line short to ground
MAF sensor/IAT sensor 1 VCC line short to ground
Engine oil pressure sensor VCC line short to ground
Rocker arm oil pressure sensor VCC line short to ground
FTP sensor VCC line short to ground* 1
PCM internal circuit failure

*1: USA and Canada models

Diagnosis Details

Conditions for setting the DTC

When a malfunction is detected, the MIL comes on and a Pending DTC, a Confirmed DTC, and the freeze data are stored in the PCM memory.

Conditions for clearing the DTC

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.