Question about 2008 Jeep Wrangler Rubicon
New PCM plugs and wires and upper and lower bank o2sensors at 75000 miles.Replaced o2 sensor p0132 at 82000 miles check engine code comes back after clearing
New PCM plugs and wires? hun?
new harness ,why? in a fire or wreck? running off road?
or did you mean, new PCM, new spark wires, and all new 02s sensors' It wont be a bad PCM , sorry, 99% are good.
the PCM never lies. it measure this and does a test and if it fails there is a circuit fault.
the why to understand, DTCs (have a FSM factory serv. manual)
and read how the test works. or do the tests it tells you do to
to discover true cause)
i have this car v6 3.8L: and 6speed and the FSM, book.
O2 SENSOR 1/1 CIRCUIT HIGH
1/1 means bank 1 , front sensor (upsteam)
bank one means right bank, cylinder 1 side.
what does HIGH mean?
what is not clear is which side is failing, heater or CELL
this test is the CELL pin (oxy out)
the test (called a monitor) finds that pin 4 is stuck at 5v.
the o2 must be 0 to 1volt at all times.
if stuck at 5vdc then the ground is open to CELL pin 3 (wire cut)
or the 02 sensors is bad. (open)
do you know how to back probe? a skill that is must for all modern cars. use needles with your meter. (DMM) (leather needles work in a pinch sold at walfart for 1buck) needle probes are 10x better
key on and back probe pin 4, if at 5vdc or more(or near) it's wrong.
btw page 2891 shows what to do in the FSM. yah 7000 pages.
I think this pin floats to 5v if the wire is cut.
fail 2 is that pin 4 is shorted to voltage ,well , the heater runs off
of 12v and all cars (bad service) the 2 wires melt and short.
here ill list all 4 pins (key on)
1- 12v heater.
3 - ecu quite ground to 02 (cell minus)
4- CELL + out (this is the oxy signal)
pin 4 must not be at 5v or 12v, but 0 to 1 volts.
at key on or running.
one more FSM quote
Measure the voltage in reference to ground, not the (K902) O2 Return Upstream circuit.
that means pin 3 to 4, is measured for best accuracy
but 5vdc or 12vdc is gross wrong .
if the o2 is new (is)
then this quote covers most fails on most cars
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact
in the Oxygen Sensor and Powertrain Control Module connectors.
here is the wiring.
if you need more photos full size or more tests.
or have questions, ask, i'm a retired ET, (controls systems , PLCs +)
see FSM here
on CD (best of best)
Posted on Nov 19, 2014
Testimonial: "Thanks for the help. Do you have any recommendations for a voltage tester? Around 75,000 miles the check engine light came on for all 4 o2 sensors so I replaced them cleared the codes and the light came back on. The dealership said the PCM was bad and replaced it. The jeep was running fine when I dropped it off at the jeep dealer a few miles after I picked up it started running bad had the plugs and spark plug wires tested and a few were bad. I replaced them and I ran just fine. At 82,000 mile the gas cap light came on and next both upper o2 sensors I replaced both and only the right side code went away. Thanks so much for your help!"
Tests/Procedures: 1. Use the scan tool to monitor the O2 sensors. Both should start out as high as 5 volts on a cold engine but gradually come down to the 2.5-3.5 volt range. 2. If either does not, check for a good.
Posted on Nov 19, 2014
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Posted on Jan 02, 2017
SOURCE: dtc codes p0155 & p0051
I had the same problem and found out I was sold the wrong sensor, my 4.0 has four, they are all different, when you install a new sensor, you must make sure you clear the trouble code before you start the engine, ignition on engine off, that should do it, it worked for me, also if you have your own scanner and can erase the codes yourself, the wrong 02 sensor will turn engine light on with cold start, then after I erased the code it would stay off all day until the next cold start, thats when I found out my new 02 sensor was for bank 1 sensor 2, and not bank 2 sensor 1, hope this helps
Posted on Jan 19, 2009
SOURCE: Po136- bank 1 sensor 2
this code is for the 02 sensor heater...there is a relay that sends the voltage to the sensor that may have malfunctioned or there may be no voltage to it
Posted on Jan 26, 2009
SOURCE: P0155 & P0135
O2 sensors are tricky. sometimes like anything else they fail. many times though the exhaust mixture they encounter is out of their range and that shows up as a failure.since you seem to have no other problems , I would go ahead and change them, but don't be disappointed if the code shows up again (at least you know it's not the sensors.) I don't like using the process of elimination when doing repairs but sometimes you must.
Posted on Mar 16, 2009
Can't tell you exactly what is wrong but the one thing you said is of concern...Map sensor should not be full of oil. If it is, I'd want to know why. In finding the reason for that, you may also find the reason why you are having a problem.
Jeep uses two kinds of engine crank venting. you either have a pcv valve or an orifice controlled system. If either are obstructed it can overpressure the crankcase and cause all kinds of problems.
Years of experience tells me this isn't something I can guess at and be 100% sure I have the right answer but based on what you said, I'd look there first!
Posted on Feb 07, 2010
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