P0452
DTC P0452CIRCUIT 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. If the control module detects the FTP sensor signal voltage below a calibrated value, this DTC will set.
The table illustrates the relationship between FTP sensor signal voltage and the EVAP system pressure/vacuum.
CONDITIONS FOR RUNNING THE DTC
The ignition is ON.
CONDITIONS FOR SETTING THE DTC
The FTP sensor voltage is less than 0.2 volts, for more than 3 seconds.
ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
CONDITIONS FOR CLEARING THE DTC
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
- Clear the DTC with a scan tool.
DIAGNOSTIC AIDS
- The FTP sensor parameter on the scan tool should read between 2.35 and 2.85 volts with the ignition ON, engine OFF and the fuel cap removed. This represents atmospheric pressure of 0 inches H2O of vacuum.
- The FTP sensor 5-volt reference circuit is shared with the following sensors:
- The camshaft position (CMP) sensor
- The exhaust gas recirculation (EGR) sensor
- The mass air flow (MAF) sensor
- The manifold absolute pressure (MAP) sensor
- The air conditioning (A/C) pressure sensor
- The accelerator pedal position (APP) sensor 1
- The FTP sensor low reference circuit is shared with the following sensors:
- The A/C pressure sensor
- The fuel level sensors
- The APP sensor 2
- Inaccurate readings will occur if resistance measurements are taken on a FTP sensor. The FTP sensor contains an internal amplifier circuit that requires applied voltage to function properly
- To locate an intermittent problem, monitor the FTP sensor voltage with the ignition ON, engine OFF. Wiggling wires, while watching for change in the FTP sensor voltage, may help locate the area where fault may exist.
- For intermittent conditions, refer to Intermittent Conditions. Intermittent Conditions
TEST
