Dodge 2004 Neon SX2 Diagnostic Manual page 445

P0172-FUEL SYSTEM 1/1 RICH —
TEST
2 Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Install a fuel pressure gauge.
Ignition on, engine not running.
With the DRBIII , actuate the ASD Fuel System test and observe the fuel pressure
gauge.
NOTE: Fuel pressure specification is 400 KPa +/- 34 KPa (58 psi +/- 5 psi).
Turn the ignition off.
Choose a conclusion that best matches your fuel pressure reading.
Within Specification
Above Specification
Caution: Stop All Actuations.
3 NOTE: If one of the O2 Sensors Signal or Return circuits are shorted to
ground or voltage, all the other O2 Sensor voltage readings will be affected.
NOTE: After the repairs have been made, verify proper O2 Sensor operation.
If all the O2 Sensor voltage readings have not returned to normal, follow the
diagnostic procedure for the remaining O2 Sensors.
Start the engine.
Allow the engine to reach normal operating temperature.
With the DRBIII , read the O2 Sensor voltage.
Is the voltage switching between 2.5 and 3.4 volts?
Yes → Go To 4
→ Go To 9
No
4 Turn the ignition off.
NOTE: Allow the O2 Sensor to cool down before continuing the test. The O2
voltage should stabilize at 5.0 volts. Raising the hood may help in reducing
under hood temps.
Ignition on, engine not running.
With the DRBIII , actuate the O2 Heater Test.
With the DRBIII , monitor O2 Sensor voltage for at least 2 minutes.
Does the voltage stay above 4.5 volts?
Yes → Replace the O2 Sensor.
→ Go To 5
No
5 Turn the ignition off.
Disconnect the hoses at the Evap Purge Solenoid.
Using a hand vacuum pump, apply 10 inches of vacuum to the Evap Purge Solenoid
vacuum source port on the component side.
Did the Evap Purge Solenoid hold vacuum?
Yes → Go To 6
→ Replace the EVAP Purge Solenoid.
No
Continued
ACTION
Go To 3
Replace the fuel filter/pressure regulator.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - NGC.
DRIVEABILITY - NGC
109
APPLICABILITY
All
All
All
All