The JT Gladiator's OBD2 port is under the driver's side dash, left of the steering column. Plug in a scanner and you can read fault codes, live sensor data, and run basic tests — without paying a shop $150 to do it.
The OBD2 port is standard across all 2020–2024 Gladiator trims. What varies is how deep your scanner can go. Generic OBD2 readers (the $25–35 units at every auto parts store) read and clear POWERTRAIN codes: engine and transmission fault codes that fall under the universal OBD2 standard. They miss chassis, ABS, airbag, and TIPM codes — which are manufacturer-specific and require enhanced software to access.
For a JT used for trail work, enhanced access matters. A P0xxx code is visible to a basic reader; a C1234 (chassis/ABS) or U1xxx (network communication) code requires enhanced Chrysler/Stellantis protocol support. The BlueDriver ($99) covers enhanced codes for Chrysler-platform vehicles including the JT and handles most of what a trail owner needs. The OBDLink MX+ ($109) is faster and more reliable over Bluetooth for extended live data sessions. If you're doing serious wrenching — testing actuators, resetting TPMS, calibrating sensors after a suspension swap — the Autel MK808 ($269) is the right tool.
**P0128 — Coolant Temperature Below Thermostat Regulating Temperature**: The thermostat is stuck open. The 3.6L JT runs a 203°F thermostat — if coolant temperature never climbs above 185°F, the thermostat is the culprit. Replace it.
**P0171 / P0174 — System Too Lean (Banks 1 and 2)**: The engine is running lean. On the JT, this is commonly a vacuum leak, a degraded oxygen sensor, or a clogged fuel injector. Examine vacuum lines first — they're visible and cheap to replace. If fuel pressure tests normal, scan the O2 sensor live data.
**P062F — Internal Control Module EEPROM Error**: Appears occasionally after disconnecting the battery or a TIPM glitch. Clear it. If it returns repeatedly, the TIPM (Totally Integrated Power Module) may be developing an issue — a known weak point on FCA platforms.
**U0100 — Lost Communication with ECM/PCM**: Network communication fault. Usually a wiring issue or loose connector rather than a failed module. Check the ECM connectors first.
**B1B03 / B1B04 — TPMS sensor codes**: Appear after tire rotations where the TPMS ID sequence hasn't been updated. Reset TPMS via the instrument cluster menu or with an enhanced scanner after rotation.
With a live data-capable scanner connected:
Clearing a code does not fix the underlying problem — it resets the fault memory and turns off the check engine light. If the root cause is still present, the code returns within one to three drive cycles. Clearing codes before an emissions test also resets the readiness monitors — the vehicle must complete several drive cycles before the monitors set "ready," which is required to pass testing in most states. Don't clear codes before an emissions inspection unless you have time to drive 100+ miles in varied conditions.
Basic code reader (Autel AL319): ~$33. Reads and clears P-codes. Enough to diagnose most check engine lights on a stock JT. Not enough for suspension/ABS/airbag work.
Enhanced Bluetooth adapter (BlueDriver or OBDLink MX+): $99–109. Pairs with a phone app and covers manufacturer-specific codes. The right choice for a JT owner who does their own maintenance and trail repairs.
Bi-directional scanner (Autel MK808): ~$269. Adds the ability to command actuators, reset learned parameters, and perform module-specific tests. Worth it if you're doing suspension swaps, sensor replacements, or TIPM-adjacent work.
Dealer-level scan tool (Stellantis StarScan/wiTECH2): Not available for consumer purchase. A dealer or well-equipped shop is required for calibration procedures and software updates that require OEM-level access.
| Part | Vendor | Est. price |
|---|---|---|
| Autel AutoLink AL319 OBD2 Scanner | Autel | ~$33 |
| BlueDriver Bluetooth OBD2 Scanner | BlueDriver | ~$99 |
| Autel MaxiCOM MK808 Bi-Directional Scanner | Autel | ~$269 |
| OBDLink MX+ Bluetooth Adapter | OBDLink | ~$109 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.