P03A7: Cylinder 2 Pressure Variation High

What it means

Cylinder-to-cylinder pressure variation on cylinder 2 is above the calibrated maximum — combustion is unstable cycle-to-cycle, typical of partial misfire or injector seat erosion.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The cylinder 2 pressure sensor measures combustion pressure over successive cycles, allowing the engine control module to detect unstable combustion. This code sets when cylinder 2's pressure varies more than the calibrated limit, which can result from a partial misfire, injector problem, low compression, or a faulty sensor.

Common causes

Most likely first.

1. Unstable combustion or partial misfire
2. Faulty cylinder 2 pressure sensor
3. Fuel injector fault
4. Low compression in cylinder 2

Symptoms

• Check engine light on
• Rough idle or engine misfire
• Shaking or vibration
• Reduced power

How to diagnose it

1. Record freeze-frame data and graph cylinder 2 pressure live data to confirm when the high cycle-to-cycle variation occurs.
2. Check for cylinder 2 misfire and related fuel or ignition codes, and compare its readings with the other cylinders.
3. Inspect the cylinder 2 pressure sensor connector and wiring for damage, corrosion, or a loose connection.
4. Check cylinder 2 injector operation and connections for signs of inconsistent fueling.
5. If sensor and injector checks do not explain the variation, compare cylinder 2 compression with the manufacturer's specification and other cylinders.

Common fixes

• Repair a loose or damaged cylinder 2 sensor connector or wiring.
• Repair or replace a confirmed faulty cylinder 2 injector.
• Replace the cylinder 2 pressure sensor if its readings are erratic despite a sound circuit.
• Repair the cylinder 2 compression problem if testing confirms leakage or cylinder damage.

Can I keep driving?

Avoid heavy acceleration if the engine is shaking or misfiring, and arrange diagnosis promptly. Continued misfire can overheat and damage the catalytic converter, while a compression problem may worsen.