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97 Jeep ZJ 4.0L Engine Stalls with Multiple OBD2 Codes: P0340, P0118, P0108, P0351, P0113, P0138 - Diagnosis & Fixes

Model: 97 Jeep ZJ Fault Code: P0108 Posted: 2016-07-31 21:22

Hi everyone, first-time poster with a 1997 Jeep Grand Cherokee Laredo 4.0L engine. I've diagnosed multiple OBD2 fault codes using an Actron scan tool: - P0340: Cam Position Sensor (CMP) circuit high voltage - P0118: Engine Coolant Temperature (ECT) sensor high voltage - P0108: Manifold Absolute Pressure (MAP) sensor high voltage - P0351: Coil primary circuit fault - P0113: Intake Air Temperature (IAT) sensor high voltage - P0138: Oxygen Sensor 2 (after catalytic converter) high voltage Vehicle details: - No aftermarket remote start or alarm systems - Installed a new Mopar CPS two years ago - Fuel pressure has not been tested yet - All sensors have been verified with a digital multimeter (DVM) and are within specification Symptoms: - Slight rough idle - Random stalling — often I feel it miss, then shift to neutral and rev the engine to prevent shutdown - Sometimes starts for 1–2 seconds before dying, repeating until it runs steadily - Occasionally, after sitting for hours or overnight, it starts immediately without issue (very inconsistent) All sensor readings show 'high voltage' — this is unusual and raises concerns about wiring, grounding, or ECU input integrity. I've rebuilt the 4.0L engine several years ago, so I'm looking for expert insights on where to start diagnosing. Any suggestions on how to troubleshoot these codes systematically? What should I check first? Thanks in advance for your help — I'll update with results after testing!

Related fault codes
P0108P0118P0138P0340P0351
Comments (12)
Anonymous 2016-07-31 21:25

Note: When the vehicle stalls, it sometimes does so with a loud backfire — like a bang. This suggests possible misfiring or fuel-air imbalance.

Anonymous 2016-08-01 07:03

The vehicle is stock. P0340 specifically points to a Cam Position Sensor (CMP) circuit issue — see https://www.obd-codes.com/p0340. Could you share the freeze frame data for these codes? For P0118, P0108, and P0113: what are the signal and reference voltages? Check the K4 ground connection for stray voltage — this is a common cause of sensor reading errors. For P0138, what is the return voltage on the O2 sensor? Also, check TPS function and any issues with cruise control or horn operation.

Anonymous 2016-08-01 16:26

The horn works intermittently; cruise control operates but cannot maintain a steady speed.

Anonymous 2016-08-01 18:26

I'll inspect the K4 ground connection and report back with findings.

Anonymous 2016-08-01 21:06

You're right — P0340 is actually a CMP circuit issue. I misread my notes earlier. Corrected list of codes: P0340, P0123, P0118, P0108, P0351, P0113, P0138

Anonymous 2016-08-02 07:50

Any airbag light or other related DTCs? I just added a TPS code (P0123). Freeze frame data might reveal key parameters — check for relevant values during fault conditions.

Anonymous 2016-08-02 18:18

Yes, the TPS is also showing a fault. The gauges behave erratically — especially at lower temperatures. They seem to function better when ambient temperature rises.

Anonymous 2016-08-02 18:19

No airbag light or other warning codes are present.

Anonymous 2016-08-03 22:19

I own a 1996 Jeep Grand Cherokee — I'm also experiencing P1457 and severe stalling. The stall happens so quickly that I don’t have time to shift into neutral or rev it up. Same issue — hoping for some insight on what could be causing this.

Anonymous 2016-08-04 15:44

Try wiggling the three ECU connectors while the engine is running — if the vehicle stalls, that strongly suggests a loose or intermittent connection.

Anonymous 2016-10-25 10:47

I have a 2006 Jeep Commander with a persistent check engine light. The shop diagnosed it as P0138 and replaced the O2 sensor — the code remains. What else could be causing this? Any wiring or ECU-related issues?

Anonymous 2016-10-25 12:34

What engine type is in your Commander? Regarding P0138: Oxygen Sensor Circuit High Voltage (Bank 1, Sensor 2) — this code often indicates a wiring fault or the use of inferior aftermarket parts. A scanner can help identify what voltage the PCM is actually detecting. Important note: An OBD2 code does not always mean a part needs replacement — it may point to a signal issue, grounding problem, or sensor circuit interference.