Circuit Description
The EVAP Pressure sensor is a sensor that changes resistance based upon fuel tank pressure (or vacuum). A vacuum is considered negative pressure.
The PCM provides a 5 volt reference and ground. The EVAP Pressure sensor signal varies between ground and 5 volts as fuel tank pressure varies. As pressure decreases (negative pressure, or vacuum), voltage increases. As pressure increases, voltage decreases (positive pressure, low voltage). The PCM uses the EVAP Pressure sensor values as an indicator of EVAP system efficiency. If the EVAP Pressure sensor signal goes low such as when the signal line is shorted to ground or the EVAP Pressure sensor is shorted internally, this DTC will set.
Conditions for Running the DTC
| • | DTC P0601 is not set. |
| • | Fuel level at engine start up is the same or less than 85% full. |
| • | The Intake Air Temperature (IAT) at engine start up is between 2°C and 60°C. |
Conditions for Setting the DTC
The EVAP Pressure sensor reading has been 0.17 volts or lower.
Action Taken When the DTC Sets
| • | PCM turns ON the SERVICE EMISSION SYSTEM message. |
| • | PCM disables Evaporative Emission (EVAP) control solenoid. |
| • | The PCM will illuminate the Malfunction Indicator Lamp (MIL) after two consecutive drive trips that the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the DTC sets. This information will be stored in the Freeze Frame and Failure Records. |
| • | A first failure of this DTC will store in Last Test Failed but not History. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A Last Test Failed DTC will clear when the diagnostic runs and does not fail. |
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any diagnostic test. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in Powertrain Control Module Description . |
Diagnostic Aids
The EVAP Pressure Sensor monitors a range from 7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).
This vehicle is equipped with an access panel in the trunk compartment.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
If the EVAP Pressure sensor or circuitry are open, the sensor parameter will read 0.22 volts or less.
-
Checking if circuitry from sensor to PCM is able to respond to a 5 volt signal on the EVAP Pressure sensor input. A reading of 5 volts means wiring and PCM are OK.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | |
Is the value displayed the same or less than the value specified? | 0.22 volts | Go to Step 3 | Fault not present. Go to Diagnostic Aids. | |
Is the value displayed higher than the value specified? | 4.80 volts | Go to Step 14 | Go to Step 4 | |
4 |
Is the voltage in the range specified? | 4.7 - 5.3 volts | Go to Step 5 | Go to Step 7 |
5 |
Is the resistance less than the value specified? | OL | Go to Step 10 | Go to Step 6 |
6 |
Is the voltage in the range specified? | 4.7 - 5.3 volts | Go to Step 11 | Go to Step 16 |
7 |
Is the voltage higher than the value specified? | 0.1 volts | Go to Step 8 | Go to Step 9 |
8 |
Is the resistance more than the value specified? | 5 ohms | Go to Step 12 | Go to Step 16 |
9 |
Is the resistance less than the value specified? | 10K ohms | Go to Step 13 | Go to Step 16 |
10 | Repair the short to ground in the EVAP Pressure Sensor Signal circuit. Is the repair complete? | -- | -- | |
11 | Repair the open in the EVAP Pressure Sensor Signal circuit. Is the repair complete? | -- | -- | |
12 | Repair the open in the 5 volt Reference circuit. Is the repair complete? | -- | -- | |
13 | Repair short to ground in CKTs with low resistance. Is the repair complete? | -- | -- | |
14 |
Was terminal contact repaired? | -- | Go to Step 15 | |
15 | Replace the EVAP Pressure sensor. Refer to EVAP Pressure sensor replacement. Is the replacement complete? | -- | -- | |
16 |
Was terminal contact repaired? | -- | Go to Step 17 | |
17 | Replace the PCM. Refer to Powertrain Control Module Replacement . Is the replacement complete? | -- | -- |
