Jeep check engine codes

Overview

Jeep shares engines with Chrysler, Dodge, and Ram. EVAP faults, thermostat codes, misfires, and throttle position faults all appear; diagnose them the same way as on other vehicles.

Codes notably common on Jeep

• P0456 Evaporative Emission System Very Small Leak Detected
• P0455 Evaporative Emission System Large Leak Detected
• P0128 Coolant Thermostat (Coolant Temperature Below Regulating Temperature)
• P0300 Random or Multiple Cylinder Misfire Detected
• P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Jeep specific notes

• P2135 is diagnosed the same way on Jeep as other vehicles: inspect the throttle body connector and wiring and compare both sensor signals before replacing the throttle body.
• The 3.6 Pentastar V6 has FCA service guidance for oil filter housing leaks, often seen as oil pooling in the engine valley.
• Chrysler guidance for EVAP codes calls for a smoke test before replacing the ESIM.

Owner's manuals

Official Jeep owner's manual / owner portal (manufacturer site; we do not host copies).

Recall lookup

Check open Jeep recalls with your VIN at the NHTSA recall lookup.

Sources

• https://static.nhtsa.gov/odi/tsbs/2019/MC-10162477-9999.pdf
• https://dot.report/bulletins/10119601
• https://www.nhtsa.gov/recalls

Sources checked October 2026. Bulletins apply only to the models and years they list.

All other codes

These work the same on Jeep as on any vehicle:

P0430 P0301 P0302 P0303 P0304 P0171 P0174 P0440 P0442 P0135 P0141 P0101 P0299 P2135 P0401