P0520 Code: Honda Accord (2018-2023) - Causes, Symptoms & Fixes

Diagnostic guide for OBD2 code P0520 on 2018-2023 Honda Accord

Important data note (per the provided dataset)

• OWNER COMPLAINTS: No NHTSA complaints found for this make/model/year/issue combination.
• OFFICIAL RECALLS: No recalls found in NHTSA database.
• No recalls found in NHTSA database (as requested by the data).
• The guide uses general automotive knowledge for technical explanations and is limited by the available dataset.

CODE MEANING AND SEVERITY

• What P0520 means:

  • P0520 is the Engine Oil Pressure Sensor/Switch Circuit fault code. It indicates the PCM (engine computer) detects a problem in the circuit that senses engine oil pressure. This can be caused by a faulty oil pressure sensor/switch, poor wiring or connector condition, or an actual abnormal oil pressure condition the PCM interprets as out of range.

• Severity on a 2018-2023 Honda Accord:

  • The code can indicate two scenarios:
    1. A true oil pressure problem (low oil pressure) which can cause severe engine damage if not addressed promptly.
    2. A sensor/wiring fault that gives an incorrect reading even when oil pressure is normal.
  • Because oil pressure is critical for lubrication, a genuine low oil pressure situation is high risk and can trigger warning lights and potential engine shutdown or limp mode to protect the engine. A faulty sensor or wiring is lower risk by itself but should be corrected to avoid misdiagnosis and potential misbehavior of the engine management system.

COMMON CAUSES ON HONDA ACCORD

• Faulty oil pressure sensor (most common cause for P0520 on many vehicles, including Honda).
• Damaged, corroded, or loose wiring to the oil pressure sensor or its connector; broken/pinched harnesses.
• Poor electrical ground or a faulty 5V reference to the sensor from the PCM.
• Low oil level or degraded oil quality (old/contaminated oil, incorrect viscosity) leading to legitimately low oil pressure.
• Oil pump issues (weak pump, worn rotor, clogged screens) or blocked oil passages causing lower than expected pressure.
• Engine mechanical wear (bearing wear, excessive clearance) leading to chronically low pressure in some situations.
• Short to power, ground, or interference on the sensor circuit (e.g., shorts to 5V or open circuits in the wiring).
• PCM or software-related ground/reference issues (less common, but possible in some cases).

SYMPTOMS (in addition to the check engine light)

• Illumination of the CEL (Check Engine Light) with P0520 stored.
• Oil pressure warning light or an abnormal oil pressure gauge reading on the dash (if equipped with a gauge).
• Occasional or intermittent oil pressure readings that don’t match the actual engine condition (sensor fault).
• In a genuine low oil pressure condition: engine knock/abnormal noises, oil pressure warning, reduced engine performance, or, in severe cases, engine damage risk.
• Engine may run normally if the sensor is faulty but the actual oil pressure is okay; this can lead to confusing symptoms where the light is on but the engine sounds fine.

DIAGNOSTIC STEPS (step-by-step, practical flow)

Note: Use a reputable OBD2 scanner to pull P0520 and view freeze-frame data, live data, and any related codes (P0521, P0522, P0523, etc.). The following steps assume you have basic hand tools and the ability to work safely around a hot engine.

A. Initial verification

• Confirm P0520 is present and note any related codes (P0521, P0522, P0523, etc.).
• Check for any recent work on the engine or electrical system that could affect the sensor circuit.

B. Visual inspection and basic checks

• Check engine oil level with the engine cold and on a level surface. Top up to the recommended level if low.
• Inspect engine oil condition. If oil is very dirty or sludge-filled, consider an oil change and possibly a cleaning/flush (per owner’s manual guidance).
• Look for obvious oil leaks around the sensor, oil filter, and oil pressure sensor wiring.
• Inspect the wiring harness to the oil pressure sensor:
  • Look for damaged insulation, chafing, or loose connectors.
  • Check for bent, corroded, or pushed-out pins in the connector.

C. Sensor and circuit testing (non-destructive checks)

• Sensor connector test:
  • Disconnect the oil pressure sensor connector and inspect the pins for corrosion or damage.
  • Reconnect securely and ensure a firm connection.
• Wiring continuity and resistance:
  • With the key off, check the wiring from the sensor to the PCM for continuity (no opens) and check for shorts to ground or power.
  • Wiggle the harness while monitoring live data to see if readings change, which could indicate a loose or intermittent connection.
• 5V reference and ground checks:
  • If you have the service manual or access to wiring diagrams, verify the oil pressure sensor’s signal circuit is getting a stable 5V reference and a solid ground from the PCM. A drop or fluctuation can cause false readings.

D. Sensor testing (dynamic)

• Replaceable test (if you have a spare):
  • If available, swap a known-good oil pressure sensor to see if the code clears and data reads normally.
• Live data comparison:
  • Use a scan tool to view the oil pressure sensor data (and if available, actual oil pressure data via a mechanical gauge comparison).
  • If the sensor reading looks erratic or out of the expected range while the mechanical oil pressure is within spec, the sensor or its wiring is likely the culprit.

E. Mechanical oil pressure check (if the sensor test and data are inconclusive)

• Mechanical oil pressure test (advanced):
  • Attach a mechanical oil pressure gauge to the engine (where the sensor reads) to measure actual oil pressure under various conditions (idle, warm, at higher RPM).
  • Compare the measured pressure to the expected range for the specific Accord engine (see below for general ranges and notes).
  • If actual pressure is within spec but the sensor reads out of spec, focus on wiring/sensor; if actual pressure is low, address mechanical causes (oil pump, oil passages, bearing wear, etc.).

F. Decision point

• If actual oil pressure is confirmed to be normal:
  • Replace the oil pressure sensor (and inspect/repair wiring as needed) and re-test.
• If actual oil pressure is low:
  • Investigate mechanical causes (oil pump, screens/filters, oil passages, engine wear). Address oil level and quality as a first step, then consider professional service for deeper inspection.

G. Post-repair verification

• Clear the codes with the scan tool.
• Start the engine and monitor oil pressure sensor data and oil pressure gauge (if equipped) across a full driving cycle.
• Drive normally and recheck for reoccurrence of P0520 and any related codes.

Notes on engine oil pressure testing

• Actual oil pressure varies with engine speed, temperature, and engine design. Typical hot oil pressure ranges are device- and engine-specific, but common ranges for many modern engines when hot at idle are in the tens of psi, rising with RPM. If you have access to a service manual or Honda’s factory spec data for the 2018-2023 Accord variants (1.5L turbo, 2.0L turbo, etc.), use those numbers as the baseline.
• If you do not have a mechanical gauge, rely on the scan tool’s live data and the vehicle’s warning indicators to guide you, but remember that sensor faults can mimic genuine pressure problems.

RELATED CODES

• P0521: Engine oil pressure sensor range/performance
• P0522: Engine oil pressure sensor circuit low input
• P0523: Engine oil pressure sensor circuit high input
• Other oil-related codes (less common but possible in a cascading issue): P0460 (fuel level or sensor) or P0610 (controller fault) may appear if there are broader electrical or sensor problems. Primary focus should be P0520-related sensor/wiring issues.

REPAIR OPTIONS AND COSTS (2025 prices)

Note: Prices vary by region, shop, and whether you use OEM or aftermarket parts. All figures are rough, typical ranges for the United States as of 2025.

• Oil pressure sensor replacement (most common fix when the sensor is the fault)

  • Parts: $15–$60 (aftermarket sensor) or $40–$120 (OEM)
  • Labor: 0.5–1.0 hour
  • Estimated total: $60–$210

• Wiring harness/connector repair or replacement (if the fault is wiring/connector damage)

  • Parts: $5–$50 (wiring repair materials or connector)
  • Labor: 0.5–1.5 hours
  • Estimated total: $60–$180

• Oil change and filter (often prudent if testing involved oil level/quality)

  • Parts: $15–$40 (oil and filter)
  • Labor: 0.5 hour (often included with other work)
  • Estimated total: $30–$70

• Oil pump replacement (if actual oil pressure is confirmed low due to pump issues)

  • Parts: $100–$450
  • Labor: 3–6 hours
  • Estimated total: $450–$1,500

• Engine internals or significant wear (bearings, mains) due to chronic low pressure

  • Parts: Highly variable; hundreds to thousands
  • Labor: 8–20 hours (or more)
  • Estimated total: $1,000–$7,000+ (depending on extent)

• PCM/ECU-related fixes (rare)

  • Parts: $0–$800 (if dealer reflash or replacement is needed)
  • Labor: 1–4 hours
  • Estimated total: $100–$1,200

Important notes about costs

• Labor rates vary widely by shop and region; urban areas tend to be higher.
• OEM parts tend to be pricier than aftermarket equivalents but may ensure better fit and reliability.
• If a sensor replacement resolves the issue, you may save on labor that would have been required to diagnose deeper mechanical causes.

DIY vs PROFESSIONAL

• DIY-friendly tasks:

  • Visual inspection of oil level and condition.
  • Inspecting and reseating the oil pressure sensor connector.
  • Basic wiring checks for obvious damage (without specialized equipment).
  • Replacing the oil pressure sensor if you have the tool set and are comfortable working around an engine.
  • Simple mechanical oil pressure checks if you have a gauge and the know-how.

• Professional tasks:

  • Verifying actual oil pressure with a mechanical gauge (requires tools and safe procedures).
  • Testing 5V reference and PCM grounds with a multimeter and wiring diagrams.
  • Diagnosing parasitic electrical issues, harness faults, or PCM-related faults.
  • Replacing an oil pump or performing deep engine work if mechanical wear is found.

Safety and best practices:

• Always work on a cool engine and secure the vehicle properly.
• Dispose of used oil and filters responsibly.
• If you’re unsure about pressure testing or wiring diagnostics, seek professional help—incorrect testing or wiring work can cause further damage.

PREVENTION

• Regular oil changes with the recommended grade and specification for the Accord (consult the owner’s manual for the exact oil type and interval).
  • Using the correct viscosity and quality oil helps maintain proper lubrication and oil pressure.
• Replace the oil filter at each oil change; use high-quality filters.
• Check oil level monthly and before long trips; immediately address any oil leaks or consumption.
• Follow maintenance schedules for oil coolers, oil coolants, and oil passages to minimize sludge buildup (especially in older engines or if you drive in harsh conditions).
• If you notice any oil consumption increase, unusual engine noises, or warning lights, diagnose promptly rather than continuing to drive.

Summary

• P0520 on a 2018-2023 Honda Accord indicates an issue with the engine oil pressure sensor circuit, which could be caused by a faulty sensor, wiring/connector problems, or an actual abnormal oil pressure condition.
• The dataset for this specific model/year shows no NHTSA complaints or recalls in the provided data, but that does not guarantee the absence of issues in general.
• Start with a thorough check of oil level/quality and inspect the sensor wiring and connector. If the sensor and wiring test good, verify actual oil pressure with a mechanical gauge to determine if the issue is sensor-related or a genuine mechanical problem.
• Replacing the sensor is the most common first repair for P0520; if oil pressure is low, expect possible pump or engine wear repairs, which can be significantly more expensive.
• As always, use a cautious, methodical approach and consider professional service if you’re not comfortable performing electrical or pressure tests on your own.

If you’d like, I can tailor a model-specific troubleshooting list for your exact Accord engine variant (1.5L vs 2.0L turbo) and provide a more precise wiring diagram-based test plan.