P0301 on Chrysler: How to Diagnose & Fix

The 5.7L HEMI V8 suffers from an MDS lifter design defect in which the needle bearings are undersized. Lifters can be starved of oil during idle, causing seizure and catastrophic camshaft wear leading to engine failure.

PT Cruisers are extremely prone to overheating from multiple causes: radiator fan relay failure, fan motor failure, thermostat sticking closed, radiator clogging, and water pump failure. The high-speed fan relay is the most frequent single failure point. Overheating leads to head gasket failure. This is one of the most universally reported problems across all model years.

Head gasket failure is common, especially on turbo models. The aluminum cylinder head is susceptible to pitting from acidic coolant which compromises the gasket seal. Turbo models experience higher cylinder pressures that accelerate failure. Overheating from cooling system issues frequently triggers head gasket failure.

The turbocharger on GT and turbo models fails from oil starvation, wastegate actuator failure, and bearing wear. Failures reported as early as 60,000-78,000 miles. Turbo failure is often followed by head gasket failure within months due to changes in combustion pressure dynamics.

Owner reports for these vans point to two separate cooling problems. The first is a water pump leak. Coolant drips from a small hole on the back of the pump, on the passenger side just behind the front wheel. That hole is a vent behind the pump's internal seal, so coolant coming out of it means the seal has failed. Owners report having to keep topping up coolant. The second is the radiator fans not switching on. The engine then overheats in slow traffic or at idle, the A/C cools poorly when the van is not moving, and the engine computer may store code P1491 (radiator fan relay circuit). The fan problem can be the relay, its wiring or fuse, the coolant temperature sensor, or the fan motors themselves. Shops sometimes replace the thermostat during a water pump job. If the engine keeps overheating, the head gasket can be damaged, so stop driving when the gauge climbs.

The 3.6L Pentastar V6 in Pacifica models suffers from engine stalling due to loose battery ground connections on stop/start-equipped 2017-2019 vans (recall NHTSA 19V348), crankshaft position sensor sync loss on 2017 vans (recall NHTSA 18V049), and premature head gasket failures typically around 75,000-85,000 miles. Cooling system failures can lead to coolant entering the combustion chamber, requiring complete engine replacement.

The MDS-equipped 5.7L HEMI is prone to lifter and camshaft failure. The roller lifters' needle bearings are hard for oil to reach and can fail when oil is degraded or the engine idles for long periods, causing catastrophic camshaft wear. Persistent ticking that worsens over time indicates lifter failure in progress.

The 3.6L Pentastar V6 has a documented valvetrain defect involving the rocker arms and their roller lift pins and the associated hydraulic lifters. The roller on a rocker arm can prematurely wear, loosen and drop, shifting the rocker out of alignment so it scrapes the camshaft and generates metal debris that contaminates the oil and circulates through the engine. Symptoms include a persistent ticking/tapping noise, misfires, hesitation/bucking, rough running and loss of power, and in severe cases catastrophic engine failure requiring a full engine replacement. A proposed class action against FCA US alleges the automaker knew of the valve-train defect in 2014-2020 model year vehicles (the complaint names the 2016-2020 Chrysler Pacifica, which shares the Voyager's platform and engine, but does not name the Voyager); ECM software governing lifter timing was also implicated.