P0325/ 04 4.7 ho - JeepForum.com
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post #1 of 10 Old 07-25-2021, 04:13 PM Thread Starter
blueseasons
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P0325/ 04 4.7 ho

I have owned it for just under a year. I was getting this Code after I took possession. After clearing it several times I found out the PO was using regular gas. I ran a couple tanks of Premium, cleared the code and it stayed away until today.

I have read it may not be the knock sensors, and could be the o2 sensors. I have 4.

1. Is there a replacement schedule for these or do you wait till they start failing? 139 k on the engine.
2. Does the "MOPAR Only" sensor rule apply to these?
3. Or might DENSO sensors work since some of the other electronics are DENSO.
4. One Cat is right under the engine rear seal. Yes. This one leaks a little. Would the dripping oil on the Cat effect sensor function?

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post #2 of 10 Old 07-25-2021, 04:54 PM
jtec
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p0325 is NOT o2 sensor.
The code is KN (knock sensor) P0325-KNOCK SENSOR #1 CIRCUIT. notice the key word.

First I would ask is engine pinging?
Are there ANY other codes?
Jeep powerplant is STOCK?

Check the KS sensor connector -located by inj #8. tight connection, corrosion.
Can you access this connector and use a DVOM?
The HO uses a special plug be sure correct plug. RC7PYCB4 .040 gap

With a scanner you might look at live data, ECT, Fuel trims long and short, pre cat o2 sensor readings.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 10 Old 07-25-2021, 07:01 PM Thread Starter
blueseasons
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I know its not a code for an o2 sensor. I read in another posting on this forum that for some reason it could be either 02 or knock. I am hoping its not a knock sensor. Thats way too involved for me to replace and expensive to have someone do it. I looked at the 4 o2sensors and I didnt see any broken wires. Its pretty clean under there.

I dont hear any pinging. I know what that sounds like. My CJ used to ping with regular gas until I seafomed the heck out of it. After a few treatments, it stopped.
Is pinging in this engine as obvious as it is in those older 4.2's?
No other codes.
Engine is stock.
I recently pulled a few plugs to see what condition they are in. I got extensive records from the PO and none of it indicated the plugs had been changed more than once and that was over 100k ago. They are the correct plugs. Gaped perfectly and clean.


I'll check the knock sensor connector tomorrow.
I have a digital multi meter. What am I looking for?

If I am going to do this " With a scanner you might look at live data, ECT, Fuel trims long and short, pre cat o2 sensor readings." i have to take it to a mechanic.

Thank You
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post #4 of 10 Old 07-28-2021, 01:51 PM
CarlJH
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if it detects any faults with the knock sensors it just uses the standard 4.7 map, it uses the knock sensors to advance the timing till it starts to hear it knocking and then retards the timing. mines had the p0325 ever since i got it, replaced the knock sensors with genuine MOPAR still has the code, so I just ignore it,doesn't set the engine light, its not like I'm needing 260 bhp all the time.
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post #5 of 10 Old 07-29-2021, 10:26 AM Thread Starter
blueseasons
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Quote:
Originally Posted by CarlJH View Post
if it detects any faults with the knock sensors it just uses the standard 4.7 map, it uses the knock sensors to advance the timing till it starts to hear it knocking and then retards the timing. mines had the p0325 ever since i got it, replaced the knock sensors with genuine MOPAR still has the code, so I just ignore it,doesn't set the engine light, its not like I'm needing 260 bhp all the time.
You are not noticing any performance issues like pinging? I don't want to damage anything. Are you running regular or premium?
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post #6 of 10 Old 08-02-2021, 04:37 AM
CarlJH
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It shouldn't ping, as it uses the standard engine map for the normal 4.7 which doesn't have knock sensors, and the compression ratio isn't much of a difference, i think 8.9 to 9.4 to 1 for the HO, plus I always put UK 99 octane premium fuel in mine.
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post #7 of 10 Old 08-02-2021, 09:03 AM Thread Starter
blueseasons
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What I have read is not having this circuit work causes engine damage. Why would they put knock sensors in an engine if it doesn't matter whether they work or not.Its been over a week and the code hasn't returned. I am not sure whats going on. Thanks.
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post #8 of 10 Old 08-02-2021, 09:35 AM
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You erased the code - it has NOT returned - you did check and not waiting for the CEL?

Lets wait and see - there are some tsts of KS and wiring but I would wait.

Let us now do you have a SCANNER, DVOM, wiring diagram, for the jeep?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #9 of 10 Old 08-02-2021, 01:24 PM Thread Starter
blueseasons
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Jtec- I never got a CEL when the code was present.. I only got the code using the OBD/key. I don't have a scanner or a wiring diagram. Using a DVOM is out of my experience level for this kind of thing. .
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post #10 of 10 Old 08-02-2021, 01:35 PM
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yes the reason I suggested NOT to wait for the CEL to come on, there are codes that do not turn on the CEL.
You have to scan to retrieve them.

Then you can check the connector is tight and check for codes again in a few weeks.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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