P2097
SYMPTOM
P2097-DOWNSTREAM FUEL TRIM SYSTEM 1 RICH
WHEN MONITORED
With the engine running in closed loop mode, the ambient/battery temperature above (-7 °C) 20 °F, altitude below 8500 ft.
SET CONDITION
If the PCM multiplies short term compensation by long term adaptive as well as a purge fuel multiplier and the result is below a certain value for 30 seconds over 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 PROBLEM
- 1/2 02 SENSOR
- (K141) 02 SENSOR 1/2 SIGNAL CIRCUIT
- (K299) 02 HEATER 1/2 CONTROL CIRCUIT
- (K904) 02 DOWNSTREAM RETURN CIRCUIT
- FUEL CONTAMINATION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Scan Tool Testing and Procedures
DIAGNOSTIC TEST
1. ACTIVE DTC
Note: Check the vehicle repair history. If the 1/2 02 has been replace make sure that the 02 sensor was properly installed and meets OEM specification.
Note: Check for contaminants that may have damaged the 02 Sensor: contaminated fuel, unapproved silicone, 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>> Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5. Powertrain Verification Test - Ver 5
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 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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
3. ENGINE MECHANICAL PROBLEM
Check for any of the following conditions/mechanical problems
AIR INDUCTION SYSTEM - must be free from leaks.
ENGINE VACUUM - must be at least 13 in. 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 (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 4
4. 02 SENSOR
Ignition on, engine not running.
Disconnect the 1/2 02 Sensor harness connector.
With the scan tool, monitor the 1/2 02 Sensor voltage.
The 02 Sensor voltage should read 5.0 volts on the scan tool with the connector disconnected.
Using a jumper wire, jump the (K141) 02 Sensor 1/2 Signal circuit to the (K904) 02 Downstream Return circuit in the 02 Sensor harness connector.
Note: The voltage should drop from 5.0 volts to 2.5 volts with the jumper wire in place.
Did the 02 Sensor volts change from 5.0 volts to 2.5 volts?
Yes>> Replace the 02 Sensor. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Go To 5
5. (K141) 02 SENSOR 1/2 SIGNAL CIRCUIT
Remove the jump wire.
Ignition on, engine not running.
With the scan tool, monitor the 1/2 02 Sensor voltage.
Is the voltage above 4.8 volts?
Yes>> Go To 6
No>> Check the (K141) 02 Sensor 1/2 Signal circuit for an open or short to voltage. Inspect the 02 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
6. (K299) 02 SENSOR 1/2 HEATER CONTROL CIRCUIT OPEN
Turn the ignition off.
Measure the resistance of the (K299) 02 Sensor 1/2 Heater Control circuit from the 02 Sensor harness connector to the appropriate terminal of special tool # 8815.
Is the resistance below 5.0 ohms?
Yes>> Go To 7
No>> Repair the open in the (K299) 02 Sensor 1/2 Heater Control circuit. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
7. (K904) 02 DOWN STREAM RETURN CIRCUIT
Measure the voltage on the (K904) 02 Downstream Return circuit in the 02 Sensor harness connector.
Is the voltage at 2.5 volts?
Yes>> Check the fuel system for contaminants. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.
No>> Check the (K904) 02 Downstream Return circuit for a short to ground, open, or short to voltage. Inspect the 02 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module per Service Information. Perform (NGC) POWERTRAIN VERIFICATION TEST VER-5.