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Grand Cherokee WJ oxygen sensor

An O2 sensor is a galvanic battery that provides the PCM v a voltage signal (0-1 volt) inversely proportional come the lot of oxygen in the exhaust. In other words, if the oxygen contents is low, the voltage output is high; if the oxygen contents is high the calculation voltage is low. The PCM uses this information to readjust injector pulse-width to accomplish the 14.7–to–1 air/fuel ratio important for ideal engine operation and also to manage emissions.

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The O2 sensor must have a resource of oxygen from outside of the exhaust stream because that comparison. Existing O2 sensors get their fresh oxygen (outside air) supply through the O2 sensor instance housing.

Four wires (circuits) are used on every O2 sensor:

12–volt feed circuit for the sensor heating elementGround circuit for the heater elementLow-noise sensor return circuit come the PCMInput circuit from the sensor back to the PCM to detect sensor operation
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Grand Cherokee oxygen sensor locations for 4.0 and 4.7 engines

The Oxygen Sensors (O2S) are attached to, and protrude right into the auto exhaust system. Relying on the emission package, the car may usage a total of either 2 or 4 sensors.

Federal Emissions package (4.0L and 4.7L engines):

Two sensors room used: upstream (referred to together 1/1) and downstream (referred to as 1/2). With this emission package, the upstream sensor (1/1) is located just prior to the main catalytic convertor. The downstream sensor (1/2) is located simply after the key catalytic convertor.

California Emissions package (4.0L engine):

On this emissions package, 4 sensors room used: 2 upstream (referred to as 1/1 and also 2/1) and 2 downstream (referred to together 1/2 and 2/2). V this emission package, the rear/upper upstream sensor (2/1) is situated in the exhaust downpipe just before the behind mini-catalytic convertor. The front/upper upstream sensor (1/1) is situated in the exhaust downpipe just prior to the prior mini-catalytic convertor. The rear/lower downstream sensor (2/2) is located in the exhaust downpipe simply after the rear mini-catalytic convertor, and also before the key catalytic convertor. The front/lower downstream sensor (1/2) is located in the exhaust downpipe just after the former mini-catalytic convertor, and also before the main catalytic convertor.

California Emissions parcel (4.7L engine):

On this emissions package, 4 sensors room used: 2 upstream (referred to as 1/1 and also 2/1) and 2 downstream (referred to as 1/2 and also 2/2). V this emission package, the appropriate upstream sensor (2/1) is located in the right exhaust downpipe just prior to the mini-catalytic convertor. The left upstream sensor (1/1) is located in the left exhaust downpipe just prior to the mini-catalytic convertor. The right downstream sensor (2/2) is situated in the best exhaust downpipe just after the mini-catalytic convertor, and before the key catalytic convertor. The left downstream sensor (1/2) is located in the left exhaust downpipe just after the mini-catalytic convertor, and before the key catalytic convertor

02S Sensor removal

Never apply any form of grease come the oxygen sensor electrical connector, or attempt any kind of soldering that the sensor wiring harness.

WARNING: THE EXHAUST MANIFOLD, EXHAUST PIPES and also CATALYTIC CONVERTER(S) BECOME really HOT throughout ENGINE OPERATION. Enable ENGINE to COOL before REMOVING OXYGEN SENSOR.

1. Raise and also support vehicle.

2. Disconnect O2S pigtail harness from main wiring harness.

3. If equipped, disconnect sensor cable harness mounting clips native engine or body.

CAUTION: once disconnecting sensor electrical connector, execute not pull straight on cable going into sensor.

4. Eliminate O2S sensor through an oxygen sensor removal and also installation tool.

02S Sensor installation

Threads of new oxygen sensors are manufacturing facility coated with anti-seize compound to help in removal. Do NOT add any additional anti-seize link to subject of a brand-new oxygen sensor.

1. Install O2S sensor. Tighten to 22 ft. Lbs. (30 N·m) torque.

2. Attach O2S sensor wire connector to key wiring harness.

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3. If equipped, attach sensor cable harness mounting clips to engine or body. Once Equipped: The O2S pigtail harness must be clipped and/or bolted ago to their initial positions top top engine or body to prevent mechanical damages to wiring.

Grand Cherokee WJ oxygen sensors

(Part Numbers: Black text = federal emissions, black color + red message = California emissions)

EngineBefore catalystAfter catalyst

1999-2000

4.0L56041676AA(w/10.5″ pigtail)56041212AE(w/18″ pigtail)56041344AD(w/14″ pigtail)56041212AF(w/12″ pigtail)
4.7L56028233AA(w/12″ pigtail)56028232AA(w/18″ pigtail) 56041345AD(w/14″ pigtail)56028235AA(w/12″ pigtail)

2001-2003

4.0L56041943AA56041944AA56041845AB5139020AA
4.7L56029333AA56041941AA56041345AE56041731AA

2004

4.0L56028995AA56028994AA56028997AA05139021AA
4.7L56044580AA56044581AA56044582AA56044583AA