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Grand Cherokee WJ oxygen sensor

An O2 sensor is a galvanic battery that gives the PCM v a voltage signal (0-1 volt) inversely proportional to the amount of oxygen in the exhaust. In other words, if the oxygen content is low, the voltage calculation is high; if the oxygen contents is high the calculation voltage is low. The PCM offers this details to change injector pulse-width to accomplish the 14.7–to–1 air/fuel ratio essential for appropriate engine operation and to manage emissions.

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The O2 sensor must have a source of oxygen from exterior of the exhaust stream for comparison. Existing O2 sensors obtain their new oxygen (outside air) supply through the O2 sensor case housing.

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

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

The Oxygen Sensors (O2S) space attached to, and also protrude right into the vehicle exhaust system. Depending upon the emissions package, the automobile may use a total of one of two people 2 or 4 sensors.

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

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

California Emissions package (4.0L engine):

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

California Emissions package (4.7L engine):

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

02S Sensor removal

Never use any form of grease to the oxygen sensor electrical connector, or attempt any kind of soldering of the sensor wiring harness.

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

1. Raise and support vehicle.

2. Disconnect O2S pigtail harness from key wiring harness.

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

CAUTION: when disconnecting sensor electrical connector, execute not pull straight on cable going right 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. Execute NOT add any additional anti-seize compound to object of a new oxygen sensor.

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

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

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

Grand Cherokee WJ oxygen sensors

(Part Numbers: Black message = 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