P2195
DTC P2195: Heated Oxygen Sensor (front) Inactive
TECHNICAL DESCRIPTION
- The ECM effects air/fuel ratio feedback control in accordance with the signals from the heated oxygen sensor (front).
- If the heated oxygen sensor (front) has deteriorated, corrections will be made by the heated oxygen sensor (rear).
- DTC P2195 becomes stored in memory if a failure is detected in the heated oxygen sensor (front).
DESCRIPTIONS OF MONITOR METHODS
Heated oxygen sensor (front) output voltage does not cross lean/rich criteria (about 0.5 volt) within specified period.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Heated oxygen sensor (front) heater monitor
- Misfire monitor
Sensor (The sensor below is determined to be normal)
- Engine coolant temperature sensor
- Intake air temperature sensor
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
- More than 300 seconds have passed since the engine starting sequence was completed.
- Engine coolant temperature is higher than 7°C (45°F).
- Under the closed loop air/fuel ratio control.
- Intake air temperature is more than -10°C (14° F).
Judgement Criterion
- Heated oxygen sensor (front) output voltage is less than lean/rich criteria (about 0.5 volt) for 128 seconds.
FAIL-SAFE AND BACKUP FUNCTION
- None
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 Monitors, Trips, Drive Cycles and Readiness Codes .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
- Heated oxygen sensor (front) deteriorated.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991658: Test Harness
STEP 1. Check the heated oxygen sensor (front).
(1)Disconnect the heated oxygen sensor (front) connector C-34 and connect test harness special tool MB991658 to the connector on the heated oxygen sensor (front) side.
(2)Warm up the engine until engine coolant temperature reaches 80°C (176°F) or higher.
(3)Rev the engine for 5 minutes or more with the engine speed of 2,000 r/min.
(4)Connect a digital voltage meter between terminal No. 3 and terminal No. 4.
(5)While repeatedly revving the engine, measure the heated oxygen sensor (front) output voltage.
(6)Standard value: 0.6 - 1.0 V
CAUTION:
- Be very careful when connecting the jumper wires; incorrect connection can damage the heated oxygen sensor.
- Be careful the heater can be damaged if a voltage beyond 8 volts is applied to the heated oxygen sensor heater.
NOTE:
If the sufficiently high temperature [of approximate 400°C (752°F) or more] is not reached although the heated oxygen sensor is normal, the output voltage would be possibly low although the rich air/fuel ratio. Therefore, if the output voltage is low, use a jumper wire to connect the terminal No. 1 and the terminal No. 2 of the heated oxygen sensor with the positive terminal and the negative terminal of 8 volts power supply respectively, then check again.
Q. Is the measured voltage between 0.6 and 1.0 volt?
YES Go to Step 2.
NO Replace the heated oxygen sensor (front). Then go to Step 3.
STEP 2. Test the OBD-II drive cycle.
(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 Monitors, Trips, Drive Cycles and Readiness Codes.
(2)Check the diagnostic trouble code (DTC).
Q. Is DTC P2195 set?
YES Replace the ECM (Refer to, Removal and Installation Removal and Replacement).
Then go to Step 3.
NO It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
STEP 3. Test the OBD-II drive cycle.
(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 22 Monitors, Trips, Drive Cycles and Readiness Codes.
(2)Check the diagnostic trouble code (DTC).
Q. Is DTC P2195 set?
YES Retry the troubleshooting.
NO The inspection is complete.