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  #1  
Old March 24th, 2016, 19:40
J33p98 J33p98 is offline
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P0463,P1391

Hey Guys

I was wondering if anyone has run into this problem. I have a 1998 xj 4.0L
I have absolutely no driveabilty problems at all, however the MIL light stays on with the following 2 codes P0463,P1391, the light will go out usually when I get to a little less then a half a tank of gas and stay out for a few starts. This has been going on for about 4 years right after I had the engine rebuild. When the light goes out I can easily get through emission inspection. I just never know how long the lights will stay out so it's pain getting it through inspection. I did replace the KPS with an OEM one 4 yrs ago but that never solved the problem.

Any information would be greatly appreciated
Thanks
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Old March 25th, 2016, 06:45
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Tim_MN Tim_MN is offline
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Re: P0463,P1391

Follow the trouble codes and begin the diagnostics and inspection with those systems/components/wire circuits.

P0463 JEEP - Fuel Level Sensor 1 Circuit High

Possible causes

- Faulty fuel level sensor
- Fuel level sensor harness is open or shorted
- Fuel level sensor circuit poor electrical connection



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.

Symptom:
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.
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Quote:
Originally Posted by bimmerjeeper

Blanket caught in the rear liftgate latch. Now I can't open.
.
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Old March 25th, 2016, 08:43
J33p98 J33p98 is offline
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Re: P0463,P1391

Thanks for the list. I originally checked the connections with the ohm meter and everything seemed correct but I'm going to recheck it again. I have read about the re-indexing but I'm little foggy on the exact procedure.I'll google the key words you posted


Thanks
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Old March 25th, 2016, 11:34
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Tim_MN Tim_MN is offline
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Re: P0463,P1391

I highly recommend you buy a genuine Jeep Service Manual. Test procedures and repair instructions are for everything in/on/under the Jeep are there. $ 7.95 at www.pacificcoastmanuals.com/
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Quote:
Originally Posted by bimmerjeeper

Blanket caught in the rear liftgate latch. Now I can't open.
.

Last edited by Tim_MN; March 25th, 2016 at 11:37.
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