2001 Cherokee Died and Will Not Start

Hi guys, I am new to the forum. I browse from time to time and find some very good info. I just joined to be able to post. I recently have encountered a problem I haven't found much info on, or seen anyone with similar issues. Here it is:

The vehicle is a 2001 XJ with the straight six, automatic, 2wd, 170K miles and bone stock. It is my wife's commuter for around town and gets driven about 100 miles a week. She was recently driving home from work and the Jeep died on her. The check engine light was not on before this mishap, and is now on. She could not get it to start after it died and we were forced to have it towed. When I got it home in my garage I plugged in my code reader and got the following eight codes:

P0353 Ignition Coil C Primary/Secondary Circuit Malfunction
P0352 Ignition Coil B Primary/Secondary Circuit Malfunction
P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
P0301 Cylinder 1 Misfire Detected
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P1391 Cam/Crank Sensor Signal Intermittent Condition
P0306 Cylinder 6 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected

I did some reading from some of the forums and started with replacing the spark plugs and coil. I replaced the Bosch Platinum plugs that the previous owner had installed with OEM NGKs (gapped at 0.035), and replaced the old coil with a new Standard OEM replacement coil. I also pulled the fuel rail, cleaned and inspected the injectors, replaced o-rings, and checked all electrical connections. I tested the fuel pressure at the rail and I am getting 42-44 psi. After attempting to start it, the engine cranks, but will not start.

I then replaced the crankshaft positioning sensor with an OEM Mopar part. $110 later, the engine cranks but will not start. I replaced the camshaft position sensor when we first purchased the vehicle about a year ago when I did the rear main seal, (160k miles on the odometer) also a new OEM Mopar part and it has never given us any problems so I do not suspect that is the problem.

The only other thing I can think that may have play a part in all this was I recently replaced all 4 O2 sensors to get the Jeep to pass smog. The check engine light had been on for about three months prior and our registration was expiring and we needed to pass smog. Two of the sensors were bad, I decided to replace all 4. I replaced them with Bosch O2 sensors, as the OEM ones were $150 a piece. After replacing all 4 O2s, the Jeep instantly idled better, had more power, and ran smoother all around. No check engine light, passed smog, everything seemed great. This was about 2-3 weeks ago, or roughly 300 miles ago, and now this problem.

I am stumped. We picked the Jeep up for $2500 and i has been great up to this point. I have only done the rear main seal, new oil pump, and new camshaft sensor after reinstalling the helical gear with #1 cylinder at tdc. I change the oil every 3000 miles and the vehicle serves its purpose.

Has anyone experienced anything similar or heard of anything like this? I have never owned a vehicle I couldn't fix, or didn't do all of my own maintenance on. I cringe at the idea of towing it to a shop, and wouldn't know who to trust or where to take it. Anyone with suggestions or info on this issue, I would greatly appreciate it!!!

check to make sure that your o2 sensor wires did not melt onto the exhaust. it might have shorted. and same thing for the crank sensor. i would focus on the crank sensor and its wiring. this is the one located on the top of the transmission bell housing.

It still seems like the crank sensor is the culprit.

check all fuses under hood and under dash passenger side in kick panel

I had the coil pack codes and the 1391 cam sensor code when I had the cheep sensor ( there when I bought it) the glue that held the magnet in the sensor failed and killed the drive from the cam. I bought a new sensor and drive. Had it running for about 5 minutes and it died about a mile from home. I had the code reader with me and the same codes were back. I went online ( still on the side of the road) and I just happened to have the tools to re-synk the cam and crank sensor. Bam. Fixed. Only have the ocational stall which I suspect is the crank sensor. I still will get the 1391 then it gets hot. But it's a stroker motor. Just my $0.02


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I will check all those today guys, thanks. I wanted to add that when I went to meet my wife after it died before having it towed I tried to start it, it did start, idled rough, it barly ran enough to where I could move it a few feet to a safer location, when I gave it throttle it really didn't respond and wanted to die. I basically got it to start and idle about 200 feet and then I shut it off. After I shut it off I was unable to get it started after that. The reason I mention this is because if it was a fuse or relay, wouldn't it have not started at all? Do these model Jeeps have a fail safe mode or limp mode?

Thanks again guys

the jeep can run with pretty much every sensor unplugged except for the crank sensor. it wont know that the engine is rotating if thats out.

The late model electronics ( when they started using coil packs) has a limp mode. It will actually stall itself if you do what I did to get it home. I had to floor it in limp mode to not get hit and after I think 3 or 5 secconds the ecu shuts down the motor. Won't restart unless you cycle the key.


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It has a new crank sensor installed. I started with the plugs and coil (I wanted to change those anyways) and after that didn't do it I moved immediately to the crank sensor. I replaced the old one which was caked with road grime/oily dirt with a new OEM one. I have triple checked all wires/connections for possible loose wires or bad connections. Everything seems to be in working condition. No loose connections in the engine bay, no loose connections on the underside near the cats or trans linkage. The engine cranks and turns over bus still will not start.

I do want to add that after installing the new crank sensor and cranking the engine without getting it to start I did disconnect the battery for a few hours after installing the new crank sensor in an attempt to trick the ECU. As soon as I hooked the battery up and cranked it over again I still am getting the same result.

I have to work tonight, I will be checking all fuses/relays tomorrow morning. I will post an update tomorrow.

As a general rule, the Jeep 4.0L and Bosch O2 sensors do not play well together. YMMV.

Inspect the O2 sensor fuses. Test the O2 sensors. Inspect the O2 Sensor/Cam Sensor/Crank Sensor wire plugs for damaged, corroded or dislodged wire pins. Check that the O2 Sensor/Cam Sensor/Crank Sensor wires are not rubbing on sharp metal or contacting hot exhaust. Test the O2 sensor wire harness continuity.

While it is incredibly rare, a faulty CPS can cause damage to the ECU/PCM. Only consider this possibility if you can get a used PCM for $30 or less or if you have exhausted all other logical and normal causes for the CEL trouble codes.


I would solve for the P1391. The other codes are likely caused by the P1391 malfunction.

P1391 - Intermittent Loss of CMP or CKP Signal. Loss of the Cam Position Sensor or Crank Position sensor signal has occurred.

P1391 – Possible symptoms:
(1) random misfire/stumble/stalling, often over bumps or right turns and when going into reverse.
(2) shorted out the fuel pump/ECU power wire.

Possible causes
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.


P1391-INTERMITTENT LOSS OF CMP OR CKP

CMP SENSOR OUT OF SYNC
-DAMAGED TONE WHEEL/FLEX PLATE (CRANKSHAFT)
-DAMAGED TONE WHEEL/PULSE RING (CAMSHAFT)
-IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL

INTERMITTENT CKP SIGNAL LOSS WHEN WIRING IS WIGGLED
-IRREGULAR LAB SCOPE PATTERN OF CKP SIGNAL
-WIRING HARNESS INTERMITTENT

INTERMITTENT CMP SIGNAL LOSS WHEN WIRING IS WIGGLED
-SENSOR CONNECTOR/WIRING
-CAMSHAFT POSITION SENSOR
-CKP SENSOR CONNECTOR/WIRING
-CRANKSHAFT POSITION SENSOR

Potential Fixes:
Fix #1:
Inspect your wire harnesses for damaged wires, chafed insulation, or failed wire splices. Use a volts/ohms multi-meter to check the resistance of the ground wire circuits from each sensor. Replace corroded ground wires/connectors and clean ground wire connection points.

Fix #2:
Timing may off. Re-index the distributor/cam sensor per the FSM instructions, or replace faulty distributor/cam sensor pickup module.

Google Scan Tools, O-Scopes and Toothpicks, and read the article.

A mis-indexed distributor/cam sensor may exhibit surging, light bucking or intermittent engine misfiring. This will most likely occur when the vehicle is at operating temperature and under a light load at approximately 2,000 rpm. The proper indexing procedure must be used as outlined in the service manual.

The fuel pump's output, at 42-44 psi, is at the lower limit for the pump.
The FSM specifies 49psi +or- 5psi.
Try checking the pressure while cranking the engine. The pump may have lost the capability to provide enough fuel to run.

Update: The Jeep Lives!!

After hours of diagnosing, checking, tightening, cleaning, inspecting, and cussing at every part on this jeep, it is back up and running again. The cause of the non-start issue was a faulty camshaft positioning sensor drive. After some very close inspection, I noticed that the cam position sensor was "clocked" just a bit more than it normally is. The sensor was not in line with the engine block, running parallel front to back. I noticed some scoring on the flange of the drive where the clamp is used to bolt the drive into place. It was scored on both sides. It is almost as if the sensor skipped a gear. I removed the cam sensor drive and when it was out of the engine, I was unable to rotate the gear that spins the shaft. The shaft was completely locked up. It appeared aftermarket. I ran the part number and confirmed that it was indeed aftermarket, made by Dorman. Summit carries this part, it is like $40 for both the sensor and the drive where as OEM parts are $79 for the sensor and $290 for the drive. Big difference in price, but you get what you pay for.

The previous owner had installed this part on the jeep. I did however replace the sensor on top of the shaft with an OEM one a few weeks after I bought the Jeep (the cheap sensor was giving me problems). I had access to a used OEM cam sensor drive here locally and was able to have it in my hands within a couple of hours. I paid very close attention when installing it, triple checking that the #1 hole was exactly at tdc, and that it was on the compression stroke and not the exhaust stroke. I used a compression guage to confirm (my fingers are too fat to fit in the hole and feel the pressure). I clocked the oil pump at 11 o'clock, lined up the ring on the drive with the outside tab, lined up the shaft that inserted into the oil pump, and dropped the used oem drive in. The sensor slid on top and lined up beautifully. After everything was tight and plugged in, the engine fired almost instantly after I cranked it.

Thank you all who gave advice and ideas on things I may have overlooked on this thing. Pay the extra $$$ and buy OEM when it comes to anything electrical on these 4.0s!

Whenever there is an issue with ignition parts or OBD sensors, always suspect after-market parts, especially the ones with a "Lifetime Warranty". People always argue when I tell them cheap parts are cheap for a reason, but this thread is another instance that proves it to be true.