How do i fix code p0108 on my wj jeep

SOURCE: 2002 wj jeep grand cherokee p1756

The governor pressure sensor is the most likley cause however an inspection of fluid or debris in trans pan would be a good idea to make sure there's nothing excessive in it. Attached is a list of possible causes however the senor would be the most common.

POSSIBLE CAUSES

• Powertrain control module
• 5 volt supply circuit open
• Check transmission fluid level and condition
• GOV press sensor signal circuit shorted to voltage
• GOV press sensor signal circuit shorted to sensor ground
• GOV press sensor signal circuit shorted to ground
• GOV pressure sensor signal circuit open
• Sensor ground circuit open
• GOV press sensor signal circuit shorted to voltage inside transmission
• 5 volt supply circuit open inside transmission
• Intermittent governor pressure solenoid
• Internal transmission problem
• Oil burnt or oil pan has excessive debris
• Other transmission DTC'S
• GOV press sensor signal circuit shorted to sensor ground inside transmission
• Valve body
• GOV press sensor signal circuit shorted to ground inside transmission
• GOV press sensor signal circuit open inside transmission
• GOV press sensor ground circuit open inside transmission
• Governor pressure sensor (high)

ZJ Limited

• 17989 Answers
• Posted on May 24, 2012

SOURCE: wj jeep 4.0 code 0420

Hi there:



The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.


You will likely not notice any drivability problems, although there may be symptoms.


A code P0420 may mean that one or more of the following has happened:

Leaded fuel was used where unleaded was called for

An oxygen sensor is not reading (functioning) properly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
******** spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings




Some suggested steps for troubleshooting a P0420 error code include:
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.

Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
Replace the catalytic converter


One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.


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