P0523: Engine Oil Pressure Sensor/Switch A High
What Does P0523 Mean?
P0523 is a diagnostic trouble code indicating: Engine Oil Pressure Sensor/Switch A High. This code relates to the vehicle speed and idle control system. It has been reported in NHTSA complaints across 1 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 P0523
- ⚠️ 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
P0523 Reports by Year
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"THE DIAGNOSTIC REVEALED THAT THERE ARE 11 CODES IN THE VEHICLE SYSTEM. THESE CODES RANGED FROM PASSKEY SYSTEM FAILURES TO EVAP CODES TO TRANSMISSION. SUSPECTED FAILURE OF WIRING HARNESS ALTOGETHER WITH POSSIBLE BCM/CAM FAILURE AS WELL. DURING BATTERY TEST THERE WAS A REGULAR DROP IN VOLTAGE WHILE CO"
— Chevrolet Impala owner, 07/22/2020
"This problem has happened for many many years. Made appointments @ Fuccillo Chevy dealer, by then it’s gone off & they don’t know! Well, just occurred again when getting new tires @Dunn pulling in. 2011 impala Stabilitrak, engine power loss, then check engine light! Thank goodness the mechanic prin"
— Chevrolet Impala owner, 11/10/2023
Source: NHTSA Complaints Database
Most Reported Vehicles for P0523
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | CHEVROLET IMPALA |
P0523 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.