DTC Advanced Diagnostics: P1458
DTC P1458:Fuel Tank Pressure (FTP) Sensor Circuit Range/Performance Problem

General Description


The evaporative emission (EVAP) leak detection system uses an engine off natural vacuum (EONV) method. The EONV method detects leakage from the change in fuel tank pressure via the fuel tank pressure (FTP) sensor with the engine off.

Here is an overview of the malfunction detection for the EONV method:

Judgment 1: Detection of atmospheric pressure failure

Judgment 2: Flickering of the FTP sensor

<Judgments 1 and 2 happen at the same time.>

Judgment 1:

After the engine has stopped, the powertrain control module (PCM) monitors the variation of the FTP sensor output to detect atmospheric pressure, after keeping the canister vent opened for a specified duration to stabilize the pressure inside the fuel tank.
If the pressure inside the fuel tank after a specified duration has not reached a specified value from the sensor zero point, a canister vent blockage is detected.

Judgment 2:

After the engine has stopped, the PCM monitors the variation of the FTP sensor output to detect FTP sensor electrical noise failure, after keeping the canister vent opened for a specified time to stabilize the pressure inside the fuel tank.
If the difference of pressure inside the fuel tank and an average value after a specified duration has exceeded a specified value for a specified duration, an FTP sensor electrical noise failure is detected.

Monitor Execution, Sequence, Duration, DTC Type
Execution
Once per driving cycle
Sequence
None
Duration
50 seconds or more
DTC Type
Two drive cycles, MIL on

Enable Conditions
Condition
Minimum
Maximum
Elapsed time before starting the engine
6 hours
–
Initial condition A*
–
36 °F (20 °C)
Initial condition B**
–
18 °F (10 °C)
Initial engine coolant temperature [ECT SENSOR 2]
40 °F (5 °C)
95 °F (35 °C)
Initial intake air temperature [IAT Sensor (1)]
40 °F (5 °C)
95 °F (35 °C)
Barometric pressure
[BARO SENSOR]
76 kPa (569 mmHg, 22.5 inHg)
–
12 volt battery voltage [BATTERY]
10.5 V
–
Other
Avoid abrupt acceleration, deceleration, and turns
Test-drive on a flat road to avoid misdetection
No refueling is required
Vehicle stopped
*: The initial intake air temperature [IAT Sensor (1)] minus the current intake air temperature [IAT Sensor (1)]
**: The initial engine coolant temperature [ECT SENSOR 1] minus the initial intake air temperature [IAT Sensor (1)]
[ ]: HDS Parameter

Malfunction Threshold
The misalignment of zero point pressure inside the fuel tank is 0.6 kPa (5 mmHg, 0.1 inHg) or more.
The output from the FTP sensor is flickering 10 seconds or more.

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.
FTP sensor output stuck
FTP sensor line electrical noise overlapped
FTP sensor line open
FTP sensor line short
EVAP canister vent shut valve full closed stuck

Confirmation Procedure
Operating Condition

1.
After the vehicle has been left for an appropriate amount of time as specified, with the engine coolant temperature [ECT SENSOR 1] and intake air temperature [IAT Sensor (1)] within the specified range, start the engine.
2.
Drive the vehicle immediately at a speed between 25 - 75 mph (40 - 120 km/h) for at least 28 minutes.
3.
After stopping the vehicle, turn the vehicle to the OFF (LOCK) mode and leave the vehicle in this condition for at least 37 minutes (EONV executes).
Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.
With the HDS
None.

Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle with the engine coolant temperature and intake air temperature at engine start-up within the specified temperature range, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle with the engine coolant temperature and intake air temperature at engine start-up within the specified temperature range, the MIL comes on and a Confirmed DTC and the freeze data are stored.

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.