Trouble codes › By vehicle › Jeep Wrangler
Common check-engine codes on the Jeep Wrangler
2007-2023
Wranglers with the 3.6L Pentastar (2012 on) share its oil filter housing and sensor problems; EVAP leaks and the 3.8L V6's oil consumption (2007-2011) are also common.
Most common: P0520, P0456, P0300, P0420, P0128, P0171.
Known problems on the Jeep Wrangler
P0520 Engine Oil Pressure Sensor/Switch "A" Circuit
P0520 means the engine computer isn't getting a usable signal from the oil pressure sensor; check the oil level before assuming it's just the sensor.
On the Jeep Wrangler: On the 3.6L, the plastic oil filter housing often leaks and soaks the oil pressure sensor in it. Replace both together. A dual-stage oil pump solenoid fault on newer engines can also set oil pressure codes.
P0520: causes, can I keep driving, and what to check first →
P0456 Evaporative Emission System Leak Detected (Very Small Leak)
P0456 means the EVAP system has a very small leak, often a gas cap that isn't sealing perfectly.
On the Jeep Wrangler: EVAP very small leaks are very common on Wranglers: gas cap, EVAP hoses near the tank and the leak detection pump or vent valve.
P0456: causes, can I keep driving, and what to check first →
P0300 Random/Multiple Cylinder Misfire Detected
P0300 means the engine is misfiring in more than one cylinder, often from worn plugs or coils, a vacuum leak or low fuel pressure.
On the Jeep Wrangler: Misfires: plugs and coils; on early 3.6L engines (2012-2013), a known cylinder head valve issue on some cylinders; check for bulletins.
P0300: causes, can I keep driving, and what to check first →
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0420 means the catalytic converter on bank 1 isn't cleaning the exhaust well enough, usually a worn converter, an exhaust leak or a lazy oxygen sensor.
On the Jeep Wrangler: Catalyst efficiency, often with P0430: check for exhaust leaks, common on older Wranglers.
P0420: causes, can I keep driving, and what to check first →
P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
P0128 means the engine isn't reaching normal operating temperature, almost always a thermostat stuck open.
On the Jeep Wrangler: Thermostat stuck open; the 3.6L thermostat housing is plastic and can leak too.
P0128: causes, can I keep driving, and what to check first →
P0171 System Too Lean (Bank 1)
P0171 means bank 1 is running lean (too much air or too little fuel), most often from a vacuum leak or a dirty MAF sensor.
On the Jeep Wrangler: Lean codes: vacuum leaks and PCV hoses.
P0171: causes, can I keep driving, and what to check first →
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Common codes and known problems as widely reported for these model years; your vehicle may differ. Check nhtsa.gov/recalls and ask a dealer about service bulletins for your VIN, and confirm in your service information.