P0520: Engine Oil Pressure Sensor/Switch A Circuit
What Does P0520 Mean?
P0520 is a diagnostic trouble code indicating: Engine Oil Pressure Sensor/Switch A Circuit. This code relates to the vehicle speed and idle control system. It has been reported in NHTSA complaints across 4 different vehicle models.
The vehicle speed and idle control systems manage engine operation at rest and in motion. The Vehicle Speed Sensor (VSS) provides real-time speed data used for fuel calculations, shift timing, cruise control, ABS, and speedometer display. The Idle Air Control (IAC) system regulates airflow to maintain target idle speed (typically 600-900 RPM). On electronic throttle control vehicles, the ECM uses the throttle body motor directly. When the ECM detects faults in these systems, drivability problems like stalling, surging, incorrect speedometer readings, and cruise control failure are common. Speed sensor failures are often caused by metal debris from internal transmission wear accumulating on the magnetic sensor tip. Idle problems are most commonly caused by carbon buildup in the throttle body restricting airflow.
Symptoms of P0520
- ⚠️ Check engine light on
- ⚠️ Erratic or inoperative speedometer
- ⚠️ Unstable idle — surging, hunting, or stalling
- ⚠️ Cruise control not working
- ⚠️ Transmission shift quality issues
- ⚠️ ABS or traction control warning light
Common Causes
- 🔍 Faulty vehicle speed sensor or idle control valve
- 🔍 Carbon buildup in throttle body
- 🔍 Vacuum leak affecting idle control
- 🔍 Wiring issue in sensor or actuator circuit
- 🔍 ECM or instrument cluster fault
P0520 Reports by Year
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"MY CHECK ENGINE LIGHT ILLUMINATED AND THE ENGINE WAS RUNNING ROUGH, POSSIBLE LOSS OF POWER. PER JEEP / CHRYSLER / DODGE / RAM / MOPAR TECHNICAL SERVICE BULLETIN 18-034-14 REV. A AND TSB-18-034-14 ON SOME MODEL VEHICLES AND JEEPS, (MY 2013-2014) THE MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATES AND"
— Jeep Wrangler owner, 11/05/2016
"VEHICLE SHOWING CEL (CHECK ENGINE LIGHT) WITH NO PERFORMANCE ISSUES NOTED. CODE READ AND SHOWS P0520 RELATED TO THE OIL PRESSURE SENSOR SWITCH. AFTER REVIEWING FORUMS, DETERMINED THAT A TSB EXISTS BUT NO RECALL ALTHOUGH THE DESIGN OF THE UNIT HAS BEEN CHANGED DUE TO DEFECT. REPLACING THIS UNIT TO"
— Jeep Wrangler owner, 01/01/2020
"P0520 - ENGINE OIL PRESSURE SENSOR CIRCUIT. TSB- 18-034-14 REV.A ISSUED: 07/15/147 THERE HAS BEEN PROBLEMS WITH THE SENSOR FOR YEARS, MULTIPLE FORUMS WITH COMPLAINTS RELATED TO THIS ISSUE IN NOT ONLY JEEP, BUT MANY CHRYSLER 3.6 LITER ENGINES. THE ADDITIONAL TROUBLE WITH JEEP IS IT IS NOT AN EASY FI"
— Jeep Wrangler owner, 09/07/2018
Source: NHTSA Complaints Database
Most Reported Vehicles for P0520
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | JEEP CHEROKEE | |
| 2 | JEEP WRANGLER | |
| 3 | DODGE DURANGO | |
| 4 | DODGE CHALLENGER |
P0520 Reports by Vehicle
Detailed NHTSA complaint analysis for each vehicle model.
Diagnostic Tips
- For speed sensor codes: check if speedometer works — if not, output speed sensor is likely bad
- For idle codes: clean throttle body first — carbon buildup is #1 cause
- Check for vacuum leaks with smoke machine
- On electronic throttle vehicles, throttle body relearn may be required after cleaning
Common Mistakes to Avoid
- ❌ Replacing idle air control valve without cleaning throttle body
- ❌ Not performing throttle body relearn after cleaning
- ❌ Ignoring vacuum leaks as cause of idle problems
Frequently Asked Questions
Why does my car idle rough after cleaning throttle body?
Can a bad speed sensor cause transmission problems?
How much does a speed sensor cost?
What To Do Next
Possible Fixes
- 🔧 Replace vehicle speed sensor
- 🔧 Clean throttle body
- 🔧 Replace idle air control valve
- 🔧 Repair vacuum leak
- 🔧 Repair wiring/connector
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1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
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Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.