P0520 on Chrysler: How to Diagnose & Fix
Engine Oil Pressure Sensor/Switch Circuit Malfunction
4 Chrysler models · 4 documented issues · 2 critical · $50-$5,000 repair
P0520 on Chrysler by model: symptoms, diagnosis and fix
The 2nd generation Concorde (1998-2004) equipped with the 2.7L DOHC V6 suffers from the same catastrophic oil sludge issue as the Intrepid and Stratus. The engine's inadequate oil drain-back passages allow oil to cook and form sludge that clogs oil galleries, starves bearings of lubrication, and causes engine seizure. The internal water pump (driven by the timing chain) is an additional failure point that can introduce coolant into the oil and dramatically accelerate sludge formation. This is widely regarded as one of the worst engine designs in modern automotive history.
Common Symptoms
- Oil pressure warning light flickering at idle
- Engine knocking or ticking noises
- Heavy sludge visible on oil filler cap
- Check engine light with misfire codes
- Sudden catastrophic engine seizure
How to Fix
Diagnosis starts with verifying low oil pressure using a mechanical gauge, inspecting under the oil filler cap/valve covers for sludge, checking for bearing noise, and testing for coolant contamination from the timing-chain-driven internal water pump. Mild cases may be addressed by removing the oil pan and valve covers, cleaning sludge from the pickup screen and oil return passages, replacing the oil pump, timing chain set, water pump, PCV valve, and performing multiple short-interval oil changes, but heavily sludged or knocking engines usually require complete engine replacement or professional rebuild. If coolant intrusion is present, the water pump and timing components must be replaced immediately, and any damaged bearings or seized rotating assembly make replacement the only practical repair. Typical costs range from about $1,500-$3,000 for partial cleanup and timing/water pump service to $4,000-$7,000+ for a quality rebuilt or replacement 2.7L engine installed.
Sources for this issue (1)
The 3.5L SOHC V6 in the 300M is susceptible to oil sludge formation, though less severely than the 2.7L. The high-performance tuning of the 3.5L in the 300M generates more heat than in other applications, and the oil drain-back passages in the heads can become restricted by sludge over time. Oil consumption of 1 quart per 1,000-2,000 miles is commonly reported. The issue is exacerbated by extended oil change intervals and conventional oil use. While not as catastrophic as the 2.7L, the sludge can lead to lifter noise, oil pressure loss, and eventually bearing damage if ignored.
Common Symptoms
- Excessive oil consumption between changes
- Lifter ticking noise on cold startup
- Oil pressure gauge reading low at idle
- Sludge visible on oil filler cap or valve cover
- Blue smoke from exhaust on startup
How to Fix
Start by verifying oil consumption and sludge severity: inspect under the oil fill cap/valve covers, check hot idle oil pressure with a mechanical gauge, listen for valvetrain noise, and perform a compression/leak-down test to rule out worn rings or valve seals. If sludge is moderate, remove the valve covers and oil pan to manually clean sludge, clear the cylinder head drain-back passages, replace the PCV valve, and refill with the correct viscosity full-synthetic oil plus a quality filter; if oil pressure is low, inspect/replace the oil pump pickup tube and screen, and repair bearing damage as needed. Engines with persistent consumption may also need valve stem seals or internal engine work, while severe sludge may justify replacing the engine rather than attempting repeated flushes, which can dislodge debris and worsen oil starvation. Typical costs range from about $300-$700 for inspection, cleaning, PCV service, and fresh oil, $800-$1,800 if oil pan/valve cover removal and pickup cleaning are required, and $2,500-$5,000+ for major internal repair or engine replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- PCV ValveCross-refPC272
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Sources for this issue (1)
The 3.5L SOHC V6 in the LHS develops excessive oil consumption over time, typically burning 1 quart every 1,000-2,000 miles. The primary causes are worn valve stem seals that allow oil to leak past the valve guides into the combustion chamber, and piston ring wear. Oil sludge formation in the head drain-back passages contributes to the problem by restricting oil return flow. Blue smoke on startup is the hallmark symptom. The issue is progressive and worsens with mileage. Extended oil change intervals and conventional oil accelerate the problem.
Common Symptoms
- Blue smoke from exhaust on cold startup
- Oil consumption of 1 quart per 1,000-2,000 miles
- Oil fouled spark plugs
- Low oil pressure at idle when hot
- Sludge buildup on valve covers and oil cap
How to Fix
Confirm the source of oil consumption by checking for blue smoke after an overnight sit, inspecting spark plugs for oil fouling, performing a compression and leak-down test, and removing the valve covers to inspect for sludge and restricted drain-back passages. If compression is good, replace the valve stem seals on both cylinder heads, clean the head drain-back areas and valve covers, install fresh spark plugs, and switch to a high-detergent synthetic oil with shorter 3,000-5,000 mile service intervals; this repair typically runs about $800-$1,800 depending on labor. If leak-down or compression testing shows worn piston rings or cylinder wear, the permanent fix is an engine overhaul or replacement short block/used engine, which commonly costs $2,500-$5,000+. Continue monitoring oil level closely between services to prevent low-oil damage and hot idle oil pressure problems.
Sources for this issue (1)
The 3.3L and 3.8L pushrod V6 engines in the New Yorker develop multiple oil leaks with age, particularly from the valve cover gaskets, rear main seal, oil pan gasket, and timing cover seal. The rubber gaskets and seals harden and shrink from heat cycling over time. While these engines are otherwise quite reliable and long-lasting, the oil leaks can cause exhaust smoke, oil dripping on the driveway, and low oil level if not monitored. The rear main seal is the most expensive repair due to labor access requirements.
Common Symptoms
- Oil spots on driveway or garage floor
- Burning oil smell from engine bay
- Visible oil on engine exterior and exhaust manifold
- Low oil level between changes
- Smoke from engine bay after extended driving
How to Fix
Diagnose the leak by thoroughly cleaning the engine, adding UV dye to the oil if needed, and inspecting common leak points on the 3.3L/3.8L V6 including the valve cover gaskets, oil pan gasket, timing cover/front crank seal, and rear main seal. Repair involves replacing the failed gasket or seal, checking the PCV/breather system so crankcase pressure is not forcing oil past seals, and resealing mating surfaces with the correct RTV where specified by Chrysler. Valve cover and oil pan gasket repairs are usually the least expensive, while timing cover and especially rear main seal repairs require much more labor because of front accessory or transmission removal. Typical costs range from about $150-$400 for valve cover or minor upper-engine leaks, $300-$700 for oil pan or timing cover resealing, and roughly $700-$1,400 for a rear main seal depending on labor rates.
Sources for this issue (1)
P0520 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0520 mean on a Chrysler?
P0520 stands for "Engine Oil Pressure Sensor/Switch Circuit Malfunction." This code indicates a general electrical fault in the circuit for the engine oil pressure sensor or switch. The computer monitors this circuit to know your oil pressure, and it has detected a signal that is missing, shorted, or otherwise out of the expected electrical range. This is typically a wiring or sensor problem rather than an actual loss of oil pressure, but because oil pressure is critical to engine life, it should never be ignored until confirmed. If oil pressure truly is low, serious engine damage can result. On Chrysler it is documented across 4 models: Concorde, 300M, LHS, New Yorker.
What are the most common causes of P0520?
The most common causes of P0520 are: Faulty oil pressure sensor or switch, Damaged, corroded, or loose wiring/connector at the sensor, Open or short in the sensor circuit wiring, Poor ground connection, Low engine oil level or genuinely low oil pressure, Failed PCM/ECM (less common). The specific cause varies by vehicle.
How much does it cost to fix P0520 on a Chrysler?
Published repair estimates on Chrysler range from $50 to $5,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0520 on a different make?
View P0520 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.