Dodge Dakota (ND). Manual — part 778
P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN
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ENGINE ELECTRICAL DIAGNOSTICS
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P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN (CONTINUED)
For the Engine circuit diagram (Refer to 9 - ENGINE - SCHEMATICS AND DIAGRAMS).
For a complete wiring diagram Refer to Section 8W.
•
When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above (-7°C) 20°F, altitude
below 8500 ft and fuel level greater than 15%.
•
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a certain percentage is exceeded for
two trips, a freeze frame is stored, the MIL illuminates and a trouble code is stored. Two Trip Fault. Three good
trips to turn off the MIL.
Possible Causes
EXHAUST LEAK
ENGINE MECHANICAL
2/2 O2 SENSOR
(K243) O2 2/2 SIGNAL CIRCUIT
(K399) O2 HEATER 2/2 CONTROL CIRCUIT
(K904) O2 RETURN DOWNSTREAM CIRCUIT
FUEL CONTAMINATION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.
ACTIVE DTC
NOTE: Check the vehicle repair history. If the 2/2 O2 has been replaced make sure that the O2 sensor was
properly installed and meets OEM specification.
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes
>> Go To 2
No
>> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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ENGINE ELECTRICAL DIAGNOSTICS
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P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN (CONTINUED)
2.
EXHAUST LEAK
Turn the ignition off.
WARNING: To avoid personal injury from the exhaust system being hot, allow the exhaust to cool down to
a safe temperature before performing a physical inspection. Failure to follow these instructions can result in
personal injury or death.
Visually and Physically inspect the exhaust system for holes, cracks, and blockage in the exhaust system.
Is the exhaust system is good condition?
Yes
>> Go To 3
No
>> Repair or Replace as necessary.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
3.
ENGINE MECHANICAL
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks
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?
Yes
>> Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No
>> Go To 4
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ENGINE ELECTRICAL DIAGNOSTICS
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P2098-DOWNSTREAM FUEL TRIM SYSTEM 2 LEAN (CONTINUED)
4.
O2 SENSOR
Ignition on, engine not running.
Disconnect the 2/2 O2 Sensor harness connector.
With the scan tool, monitor the 2/2 O2 Sensor voltage.
The O2 Sensor voltage should read 5.0 volts on the scan tool with the
connector disconnected.
Using a jumper wire, jump the (K243) O2 Sensor 2/2 Signal circuit to
the (K904) O2 Return Downstream circuit in the O2 Sensor harness
connector.
NOTE: The voltage should drop from 5.0 volts to 2.5 volts with
the jumper wire in place.
Did the O2 Sensor volts change from 5.0 volts to 2.5 volts?
Yes
>> Replace the O2 Sensor
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9
- ENGINE - STANDARD PROCEDURE)
No
>> Go To 5
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ENGINE ELECTRICAL DIAGNOSTICS
9 - 653
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