Dtc P0451; Ftp Sensor - Suzuki XL7 2007 Service Manual

1A-119 Engine General Information and Diagnosis:

DTC P0451

Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle Diagnostic Information: " prior to using this diagnostic procedure.
• Review "Strategy Based Diagnosis: " for an overview of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle Diagnostic Information: " provides an overview of each diagnostic
category.
DTC Descriptor
DTC P0451: Fuel Tank Pressure (FTP) Sensor Performance
Typical Scan Tool Data

FTP Sensor

Circuit
Operating Conditions: Engine operating in Closed Loop at idle
Parameter Normal Range: 0.2-4.8 V
5-Volt Reference Voltage
FTP Sensor Signal
Low Reference
Circuit/System Description
The control module monitors the fuel tank pressure
(FTP) sensor signal in order to detect vacuum decay and
excess vacuum during the evaporative emission (EVAP)
diagnostic test. The control module supplies a 5-volt
reference and a low reference circuit to the FTP sensor.
This DTC sets if the engine control module (ECM)
detects one of the following conditions:
• The FTP sensor signal voltage is not within a
calibrated range on a cold start-up.
• The FTP sensor signal oscillates more than a
calibrated amount when vehicle speed is less than 30
km/h (50 mph).
The following table illustrates the relationship between
FTP sensor signal voltage and the EVAP system
pressure/vacuum.
FTP Sensor Signal
Voltage
High, Approximately 1.5
Volts or More
Low, Approximately 1.5
Volts or Less
Conditions for Running the DTC
• DTCs P0100, P0101, P0102, P0103, P0116, P0117,
P0118, P0119, P0125, P0449, P0498, P0506, P0507,
P0721, P0722, P2227, P2228, and P2229 are not set.
• The engine is operating for greater than 1 second.
• The ambient air temperature is greater than −7°C
(19°F).
• The vehicle speed is between 10-30 km/h (6-19 mph).
• The ECM has commanded the EVAP canister vent
valve open for greater than 3 seconds.
• DTC P0451 runs continuously once the above
conditions are met for approximately 25 seconds.
Short to Ground
0 V
0 V
Fuel Tank Pressure
Negative Pressure/
Vacuum
Positive Pressure
Open
0 V
0 V
— 4.2 V
Conditions for Setting the DTC
• The ECM detects that the FTP is less than −11.9
inches H2O (−22.2 mm Hg) or more than 6 inches
H2O (11.2 mm Hg) for 4 seconds or for a cumulative
of 50 seconds.
• The ECM detects that the FTP sensor signal
oscillates more than 3.26 inches H20 (6.09 mm Hg)
from a zero point for 4 seconds, or for a cumulative of
50 seconds. The zero point may vary and the vehicle
speed must be between 10-30 km/h (6-19 mph) for
this test.
Action Taken When the DTC Sets
DTC P0451 is Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P0451 is Type B DTC.
Diagnostic Aids
• A blocked or clogged EVAP canister vent may set this
DTC.
• A large leak in the EVAP system could cause this
DTC to set.
Short to Voltage
5 V
5 V
—