Chrysler PT Cruiser. Manual - part 250

Symptom:

P0172-1/1 FUEL SYSTEM RICH

When Monitored and Set Condition:

P0172-1/1 FUEL SYSTEM RICH

When Monitored:

With the engine running in closed loop mode, the fuel level >15%,

atmospheric pressure >700 hpa, battery voltage >9.0 volts, air temp >-17.8°C (0°F) <-7°C
(19.4°F), coolant temp >69.75°C (157.6°F), MAF >0, canister load <50%, purge command =
0 or max, and there are no Engine Coolant Temp Sensor, Intake Air Temp Sensor, MAP
Sensor or Canister Purge Solenoid DTCs present.

Set Condition:

If fuel correction is -20 or 24% depending on load, this DTC is set

whenever the fault is detected and the MIL is turned on after the second trip with the fault
present.

POSSIBLE CAUSES

GOOD TRIP INDICATED

O2 SENSOR HEATER OPERATION

O2 SENSOR

EVAP PURGE SOLENOID OPERATION

O2 SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE

O2 SENSOR SIGNAL CIRCUIT OPEN

MAP SENSOR OPERATION

ECT SENSOR OPERATION

ENGINE MECHANICAL PROBLEM

FUEL FILTER/PRESSURE REGULATOR

PCM

TEST

ACTION

APPLICABILITY

NOTE: Check for contaminants that may have damaged the O2 Sensor:
contaminated fuel, unapproved silicone, oil and coolant.
Turn the ignition on.
With the DRBIII

t, read DTCs.

Does the Good Trip Indicator display NO?

All

Yes

→ Go To 2

→ Refer to the INTERMITTENT CONDITION symptom in the

Driveability category.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

TEST

ACTION

APPLICABILITY

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 to the fuel rail.
Turn the ignition on.
With the DRBIII

t, 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.

All

Within Specification

Go To

Above Specification

Replace the fuel pressure regulator.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

Caution: Stop All Actuations.

Turn the ignition on
NOTE: Allow the O2 Sensor voltage several minutes to stabilize before
continuing the test.
With the DRBIII

t, read the O2 Sensor voltage.

Is the voltage between 0.4 to 0.6 volts?

All

Yes

→ Go To 4

→ Go To 9

Turn the ignition off.
NOTE: Allow the O2 Sensor voltage to stabilize between 0.4 to 0.6 volts
before continuing the test.
Turn the ignition on.
With the DRBIII

t, actuate the O2 Heater Relay.

With the DRBIII

t, monitor O2 Sensor voltage for at least 2 minutes.

Does the voltage stay between 0.4 and 0.6

All

Yes

→ Replace the O2 Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Go To 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?

All

Yes

→ Go To 6

→ Replace the EVAP Purge Solenoid.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

P0172-1/1 FUEL SYSTEM RICH —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off.
Connect a Vacuum Gauge to a Manifold Vacuum source.
Start the engine.
Allow the engine to idle.
Note: If engine will not idle, maintain a constant RPM above idle.
With the DRBIII

t in Sensors, read the MAP Sensor vacuum value.

Is the DRB reading within 1

9 of the Vacuum Gauge reading?

All

Yes

→ Go To 7

→ Replace the MAP Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

Note: For this test to be valid, the thermostat must be operating correctly.
Note: This test works best if performed on a cold engine (cold soak)
Turn the ignition on.
With the DRBIII

t, read the Engine Coolant Temperature Sensor value. If the engine

was allowed to sit overnight (cold soak), the temperature value should be a sensible
value that is somewhere close to the ambient temperature.
Note: If engine coolant temperature is above 82°C (180°F), allow the engine
to cool until 65°C (150°F) is reached.
Start the Engine.
During engine warm-up, monitor the Engine Coolant Temperature value. The temp
value change should be a smooth transition from start up to normal operating temp
82°C (180°F). The value should reach at least 82°C (180°F).
Did the Engine Coolant Temperature value increase a smooth transition and did it
reach at least 82°C

All

Yes

→ Go To 8

→ Replace the Engine Coolant Temperature Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from restrictions.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?

All

Yes

→ Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Test Complete.

Turn the ignition on.
Disconnect the O2 Sensor harness connector.
With the DRBIII

t, monitor the O2 Sensor voltage.

Is the O2 Sensor voltage between 0.4 to 0.6 volts?

All

Yes

→ Replace the O2 Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Go To 10

DRIVEABILITY - 1.6L GAS

P0172-1/1 FUEL SYSTEM RICH —

Continued

TEST

ACTION

APPLICABILITY

Turn the ignition off.
Disconnect the PCM harness connector.
Disconnect the O2 Sensor harness connector.
Measure the resistance of the O2 Sensor Signal circuit between the PCM harness
connector and the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?

All

Yes

→ Go To 11

→ Check for open in the O2 Sensor Signal circuit.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

WARNING: KEEP CLEAR OF THE ENGINE’S MOVING PARTS.
Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Start the engine.
Measure the voltage of the O2 Sensor Signal circuit in the O2 Sensor harness
connector.
Is the voltage above 0.60 volt?

All

Yes

→ Repair the O2 Sensor Signal for a short to voltage.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Go To 12

NOTE: Before Continuing: Disconnect the PCM harness connector and
check the related wiring terminals for corrosion, damage or terminal push
out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay
particular attention to all Power and Ground circuits.
If there are no possible causes remaining, view repair.

All

Repair

Replace and program the Powertrain Control Module in accor-
dance with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

P0172-1/1 FUEL SYSTEM RICH —

Continued

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