Nissan X-trail Malfunction Indicator Light ON

NissanX-trailMILON

Vehicle model: Nissan X-trail

Year: November., 2009

Kind of engine: QR25

VIN: TDBNLJWT31EWAADB

Fault phenomenon:

Repair guy stated this vehicle (see Figure 1) is definitely an accident vehicle. The engine MIL (Malfunction Indicator Light) is definitely on after getting it fixed, and black smoke is eliminated from exhaust pipe.

Fault diagnosis:

The automobile, digitally controlled, have to be identified with the aid of Fcar auto diagnostic tool.

1. First, connect OBD test mind and also the primary unit with test lines correspondingly

2. Discover the location of diagnostic socket ( see Figure 2)

3.Connect diagnostic socket, and switch ignition change to ON position:

4.Switch on the energy of Fcar vehicle diagnostic scanner,

Go into the menu and choose [China]--[Nissan]--[v7.1]--[Automatic recognition system]--[Read DTC] DTC shows [P0136 HO2S2 (B2) heated oxygen sensor 2 (bank 1), P0036 HO2S2 HTR (B2) heated oxygen sensor 2 heater (bank 2)] --[Obvious DTC]--[DTC is removed effectively] --[Read DTC]--DTC shows [P0136 HO2S2 (B2) heated oxygen sensor 2 (bank 1), P0036 HO2S2 HTR (B2) heated oxygen sensor 2 heater (bank 2)]-- showing this DTC is really a true DTC.

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Fault Analysis

Based on the analysis of DTCs, it is really an abnormity triggered by short circuit of O2 sensor and harm to ECU.

Inspection techniques for oxygen sensor are the following:

1.Check of resistance of O2 sensor heater: Once the temperature from the engine is common, take away the wire connector of oxygen sensor and identify the resistance value between devices of pressure sensor with ohmmeter. The resistance value should satisfy the needs of normal worth of specific models (generally, 4-40O). When the resistance value doesn't satisfy the needs, please switch the O2 sensor.

2.Recognition of O2 sensor current output signal: After mounted the wire connector of O2 sensor, remove a wire from signal terminal, start the engine, result in the engine achieve normal operating temperature and the engine running at idle. Within this situation, please identify the output current of O2 sensor signal current. When getting rid of our prime-pressure cutoff type of a particular cylinder, oxygen content in exhaust gas will decline. When the current shown by voltmeter increases, this means the performance of O2 sensor is alright (output current of O2 sensor is usually between .2 and .9V and it is selection of variation is all about .5V. Problems to become compensated focus on throughout testing: no short circuit is permitted, the positive, negative connector of sensor terminal mustn't be ruin, the negative finish of voltmeter is attached to the negative finish of battery and also the positive finish is attached to the signal type of the sensor.

3.When checking the O2 sensor, fault cause could be known through watching the colour of the top oxygen sensor sometimes. The standard colour of the top O2 sensor is light grey. When the color changes, it signifies fault or hidden fault of O2 sensor. For instance, a black surface of O2 sensor was triggered by carbon pollution. Please obvious carbon deposit onto it after getting it removed. When the top oxygen sensor is discovered to be red-colored, this means that O2 sensor is polluted by lead, because of the leaded gasoline utilized by the automobile. Data from research has shown the purpose of O2 sensor shall lose essentially, to ensure that the 3-way catalytic ripper tools is polluted, making the purification efficiency is reduced or perhaps not function anymore, following the vehicle continues to be driven for around 500 miles with leaded gasoline. When the O2 sensor includes a whitened top, it had been triggered by plastic pollution. It is because undesirable silicone sealant can be used when repairing the engine. Now, the O2 sensor should be changed. Silica gel can also be known as 70 Degrees Vulcanization (RTV) glue. If silica gel that contains acetic acidity can be used around the engine parts where lubricating oil flows, acetic acidity is going to be evaporated into crankcase or valve areas, then passing exhaust gas recirculation system and entering intake air pipe. Under normal condition, it shall pass the engine and become exhausted from exhaust pipe, thus harmful the O2 sensor.

4.Check from the operating current of O2 sensor: turn ignition change to OFF position, take away the plug of NO.2 sensor, turn ignition change to ON position, after which measure if the current of ECU, earth wire, and signal lines are normal with multimeter. If abnormal, it signifies the circuit is shorted and also the ECU is broken at that time once the vehicle is crashed. You have to take away the harness connector of ECU and O2 sensor. Test with multimeter if the circuit is connected.

5.Look into the ECU underneath the circumstance of making certain O2 sensor and also the circuits of O2 sensor are common.

Troubleshooting:

When examining the circuits, we discovered that you will find 2 circuits aren't smooth, therefore we found the circuit of O2 sensor socket is shorted. (See Figure 3)

Following the treatment to harness short-circuited, re-install the constituents removed, turn the ignition change to ON position. Carry out the command [Obvious DTC]--[DTC is obvious effectively]. MIL is OFF. And things are OK at normal test. Unfortunately solved.

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