[jwernatl]

Hello everyone, I'm in need of some help really bad. I dont know alot, but, I know enough to be dangerous and I've done lots of research and learning about how and why the O2 sensors work.

My wife's '08 GC Limited 4.7 2wd has had the check engine light on for about a year. I pulled the code's in the beginning however I'm a disabled vet and Ive been out of work for some time now. Money's tight. The Jeep runs perfect, except for the light and all these codes.

We got our taxes back and so I'm trying fix the Jeep. I just changed the the O2 sensors - all 4 with NTK 23159 sensors. The research I've done, suggested the BOSH sensors have isues with the internal heaters not being quick enough. That's the reason I went with NTK -

Before I replaced the sensors I had these codes and 35 minutes after pulling the battery leads, swaping the sensors and driving the light came on again!

I was positive the sensors were the culprit. What gives? My buddy had a AUTOLink Autel OBDII/EOBD code reader.

Here are the codes and below that, I got this info off the scanner. I dont know how to take this information, piece it together to fix what's going on. I dont have the $ to take it to the dealer but I will last resort. If anyone could take a look at this and help I would so appreciate any help you can give. Thank you so much.

Oh and before I swaped the sensors and before I pulled the battery leads I used the code reader to clear codes. After doing that,
P1128 - P1129 - P0138 - P0158 - P0135 - P0141 - P0155 - P0161


O2 Heater Mon Bank 1 Sens 1
Meas 734
Min -40
Max 257
STS Fail

O2 Heate Mon Bank 1 Sen 2
Meas 934
Min -40
Max 302
STS Fail

O2 Heater Mon Bank 2 Sens 1
Meas 662
Min -40
Max 257
STS Fail

O2 Heater Mon Bank 2 Sens 2
Meas 941
Min -40
Max 302
STS Fail

Evap Mon .020"
Meas 36916
Min 18
Max 12
STS Fail

$cc
Volume 38.457
min 000
Max 000
STS Fail

Thank you again for any help.
John Wern Jr.

 

[jeepgcoman]

First, thanks for you service. Sorry to hear you're having problems. I don't know what the difference is with the 4.7 sensors, if any, but the sensors I used on my 05 and 06 5.7's are NTK 23160. Do you own, or have access to a DashHawk, DashDaq, UltraGauge, or some monitoriing device like that? To get a real good idea of what's going on you'll need to be able to monitor heater warm up time (time before the sensors start sampling), and actual sensor performance (number of cross counts, if any). Most of your codes indicate heater issues on all 4 sensors, except for P0138 and P0158 which are the downstream sensors (after the cats.) reading high. Without some sort of monitoring device, it'll be difficult to accurately assess what's going on, and you'll probably just end up wasting time and money trying to figure it out.

With one of the above monitoring devices you'll be able to tell how long it takes the heaters to warm up (my NTK's only take ~15-25 seconds and Bosches took ~40-45 seconds), and the PCM to switch from open loop to closed loop FI operation. If they're taking too long, it'll throw a code and, on my DashHawk, it shows an error code 8 (in addition to the DTC), for failure to switch to closed loop within the prescribed time. If you don't restart it'll remain in open loop and continue running rich. If you restart and they heat up quick enough after the initial start, it'll probably take 3 good run cycles for the PCM to clear the DTC.

The monitoring devices will also allow you to monitor sensor cross counts, if any, for all sensors. The front two should have fairly rapid cross counts above and below the approximate midpoint of .450 volts. The voltages above and below will vary and are not real critical, as long as they're switching up and down past the midpoint.

Your rear sensors (after the cats.) are only used to monitor catalyst efficiency, and should not have ANY cross counts, but may drop to a very low voltage at idle. Once warmed up and driving, they should always read somewhere above .450 volts. Without knowing what the voltages are on the 1/2 and 2/2 sensors, it'll be difficult to diagnose.

Here's a couple things that I would do, if you don't have access to any of the devices mentioned above.
--Insure you have the correct sensor part numbers installed.
--Insure all the wiring between the sensors and PCM is intact and not grounded or shorted out. Especially look for anywhere that may be chaffing and/or rubbing or pinched against something. Ground wires will either be tan or grey, and heater wires will be either brown, purple or black. If possible, you may want to "ring" these wires out (check for continuity and not grounded out) to verify their integrity.
--Insure the connector plugs are securely and completely plugged in to the sensors
--Check to insure all the grounding points on the PCM, and exhaust system (bonding wires) are in place and making good contact.

If all of these are verified good, you'll almost have to have some way of observing all sensor operations. I believe, of the monitoring devices listed above, the Ultra Gauge is the least expensive. The DashHawk is no longer available, but you may be able to find one on EBay. That's where I got my "spare". Before you purchase any though, make sure it'll read the items mentioned above.

One last thing, if you haven't already, check out the thread I did on O2 Sensors after I had problems: http://www.jeepgarage.org/f183/oxyg...role-in-engine-management-a-primer-20300.html Please keep us posted on what you find out. Good luck.

 

[2005JGC]

Denso is the OE brand on the 4.7l, honestly I would suggest you start there. Yes, bosch is the "known bad" but I have never trusted ANYTHING other than the OE on a chrysler. They are very sensitive. Especially since all the codes came up after the replacement it further points as them being the cause... Any parts store should take em back on trade for denso considering they did not work for you they are defective and for that reason alone they should take them back. Only down side, in my searches for OE brand o2 sensors when doing side work it seems they are NEVER on the shelf at the local store, infact they were hard to find in any local distribution centers, they were all on the other side of the country... wtf?

 

[jeepgcoman]

^^^Good point. I know my codes showed up immediately after installing the Bosch Sensors. Also good to know the 4.7's used Denso, and not NTK's like the 5.7. I find it amazing that there is so much variance in the sensors that are suppose to work on a given vehicle. One would hope that any brand that cross references to a particular vehicle would work.

 

[jwernatl]

Guys thank you so much. I've talked to NAPA - theyll trade me out but he asked that I find out what this means...

Evap Mon .020"
Meas 36916
Min 18
Max 12
STS Fail

$cc
Volume 38.457
min 000
Max 000
STS Fa

It was on the scanner too. I've researched it, I just cant seem to get a straight forward analysis for this code. He said he would swap me out but, he wants me to find out what this has to do with it first. thank you for your help.

 

[2005JGC]

I dont fully speak scan tool, but evap monitor .20 is going to be the small evap leak test, not sure why you dont see a dtc for small evap leak, possibly only 1 failure on a2 trip fault and you didnt check for pending codes... Not 100 % sure why.

Sent from my SCH-I500

 

[jeepgcoman]

I've never seen info. like that on my scanner, or anywhere else for that matter. I could speculate that the "meas" for the O2's is the temperature reading at which the sensor start sampling, and the "min" and "max" are the high and low millivolts read by the sensor once warmed up. Only problem with that theory is that many of those readings are completely out of the practical ranges.

I am wondering if that info. is native to the particular type scanner that produced them. You may need to see if you can get your hands on the manual(s) for the tool to get an explanation.

 

[jwernatl]

Hey guys - I put the DENSO o2Sensors in the Jeep - 30 miiles & WHAMO - ====> the check engine lights back on.

So, I droped it off at the dealer yesterday - I got a call this afternoon and they said it needs a new PCM - At first he said it would cost $775 to replace, I told him I didnt have it, there was a long silence and it seemed we were in a mexican standoff at that point, then more long silence and he said "well, I could shave a little off I guess - how's $700 to replace?".

Does it sound Logical? Sound fair?

Any input on this sure would make me feel better. any thoughts?