2002 Jeep Wrangler 4.0L Engine P1492 Fault: Battery Temperature Sensor Damaged by Squirrel Chewing - Fix & Reset Guide

Could the sensor itself be faulty? Are there any other wires damaged in addition to the main lead?

Thanks for your input. The P1492 code refers specifically to the flat thermistor mounted flush against the bottom of the battery tray, pressed directly by the lead-acid battery. This is the only fault code present and I am confident I replaced the correct part. The severed wire caused a high voltage reading (P1492) or a ground failure (P1493). According to the ACTRON manual, DTCs related to the MIL are cleared from memory after 40 engine warm-up cycles if the fault is not re-detected. However, the manual does not clarify whether certain codes will reset successfully when attempted via scan tool. Since my attempt to clear the code failed—does this mean I must complete 40 warm-up cycles, or could it be a sign of a faulty scan tool?

If a fault is cleared by disconnecting the battery or using a scan tool but persists upon re-starting the vehicle, then the repair has not been completed. Even if the MIL turns off after disconnecting the battery, it may still be stored in memory. A proper fix should result in the light staying off.

Thanks for that insight, Jeff. I replaced the thermistor pigtail with a new MOPAR part and wrapped both wires with foil reflective tape to prevent further animal damage. I inspected the area thoroughly and found no additional signs of wear. I removed the battery again to access the sensor connector, reseated it carefully (heard a snap when reconnecting), and reassembled everything. After turning on the key, the engine light flashed for about 10 seconds before going solid—a behavior I’ve never seen before. The vehicle was then restarted, and the same flashing pattern repeated. I’ll update with further results shortly. — Larry

Jeff—after disconnecting the battery and removing the sensor connector, I disconnected the two-wire inline harness from the thermistor to the PCM, inspected it thoroughly, and reconnected it. I heard a snap when it slid into place. No additional damage was visible. After reassembly and turning on the key, the engine light flashed for approximately 10 seconds before going solid. This cycle repeats every time I turn the key on. What does this flashing behavior indicate? Is there a new fault code or is it still related to P1492?

Is this vehicle a Grand Cherokee?

Jeff, this is a 2002 Jeep Wrangler with a 4.0L 6-cylinder engine and 4x4 drivetrain—approximately 12,000 miles. My spouse drives very sparingly, so mileage is low. The Jeep’s engine design has been refined over decades and is known for reliability.

So the same P1492 code persists—or has a new fault appeared?

Same code remains active.

Then the circuit is still open—the polarity may be incorrect, or the wrong sensor was installed. I suspect a faulty installation or defective part!

Thanks Jeff—I don’t believe thermistors are polarized, so they should work either way. However, the pigtail connector only allows one-way connection and cannot be reversed. The MOPAR vendor may have installed a sensor with an incorrect sensing element or an open circuit. If it were shorted, the code would be P1493 instead of P1492. What does the 10-second flashing engine light indicate?

I’m not certain about the 10-second flash—haven’t seen that behavior before. Have you checked for proper voltage on both wires between the PCM connector and the sensor connector?

Yes, I have.

Jeff—after returning to MOPAR parts, I obtained a second new battery temperature sensor and installed it. This replacement successfully resolved the issue—the engine light turned off completely. Now I’m being advised that I need to complete a long drive cycle (e.g., a trip out and back) to fully clear any pending 'monitors' from the system. Is this correct? Does the vehicle require a full drive cycle to confirm the fix?

Can your scan tool perform an I/M test to check monitor status? If any monitors are marked as 'Not Ready' or 'Incomplete,' and no active codes exist, you’ll need to complete a drive cycle (e.g., driving the vehicle for extended distance) to allow the system to fully clear pending diagnostics.