Faulty cylinder 2 pressure sensor (internal short or failure); Open or damaged wiring in the sensor signal circuit; Short to voltage on the sensor signal circuit; Corroded or loose electrical connector at the sensor; Poor ground connection for the sensor circuit; Engine computer (ECM/PCM) internal fault, though rare

DTC codes / P03xx · Ignition system and misfire / P03A2

P03A2Cylinder 2 Pressure Sensor Circuit High

Q: What does code P03A2 mean?

Cylinder 2 Pressure Sensor Circuit High. P03A2 means the engine computer has detected an abnormally high voltage signal from the cylinder 2 pressure sensor circuit, which is used to monitor combustion pressure in that cylinder. The computer expects the sensor signal to stay within a specific voltage range, and a high reading indicates an open circuit, a short to voltage, or a faulty sensor.

P03A2 means the engine computer has detected an abnormally high voltage signal from the cylinder 2 pressure sensor circuit, which is used to monitor combustion pressure in that cylinder. The computer expects the sensor signal to stay within a specific voltage range, and a high reading indicates an open circuit, a short to voltage, or a faulty sensor.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or misfire-like behavior, especially when the engine is cold
Reduced engine performance or power, as the computer may limit fuel or timing
Poor fuel economy due to incorrect fuel delivery calculations
In rare cases, the engine may enter limp mode or stall
A stored code P03A2 may be the only sign if the sensor is only intermittently faulty

Common causes, most likely first

Faulty cylinder 2 pressure sensor (internal short or failure)
Open or damaged wiring in the sensor signal circuit
Short to voltage on the sensor signal circuit
Corroded or loose electrical connector at the sensor
Poor ground connection for the sensor circuit
Engine computer (ECM/PCM) internal fault, though rare

How to diagnose and fix it

Inspect the sensor and its connector for damage, corrosion, or loose pins
Check the sensor signal circuit for an open or short to voltage using a multimeter
Verify the sensor ground circuit has good continuity to ground
Compare the sensor signal voltage with a known-good cylinder if accessible
Replace the cylinder 2 pressure sensor if wiring and connections are good
Clear the code and test-drive the vehicle to confirm the repair
If the code persists, diagnose the ECM/PCM and its programming

Before replacing the pressure sensor

A high voltage code often results from a simple open circuit or unplugged connector rather than a failed sensor, so always check connections first.
The cylinder pressure sensor is sometimes integrated with the glow plug on diesel engines, making diagnosis more complex and expensive.
This code can be set by a poor engine ground that affects the sensor reference voltage, so inspect ground straps and battery terminals.
Intermittent faults may only appear under specific conditions like vibration or temperature extremes, so wiggle-test the harness while monitoring live data.
Do not confuse this code with a misfire code; P03A2 indicates a circuit fault, not necessarily a mechanical cylinder problem.

Can I keep driving with P03A2?

It is generally safe to drive with this code if the engine is running smoothly, but avoid heavy acceleration or towing until repaired. If the engine misfires, runs rough, or enters limp mode, seek service immediately to prevent damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.