P2516: A/C Refrigerant Pressure Sensor B Circuit Range/Performance

What it means

The pressure sensor B signal is outside the expected range or does not behave as expected. The code alone does not identify whether the sensor, wiring, or pressure condition is responsible.

At a glance

• Usually lights the check-engine light

How it works

A/C refrigerant pressure sensor B measures refrigerant pressure for the control module. P2516 sets when the sensor B signal is outside the expected range or does not track pressure as expected, which can reflect a pressure issue, a drifting sensor, or its circuit.

Common causes

Most likely first.

1. Low refrigerant charge
2. Contaminated or aged sensor diaphragm
3. Sensor element aged beyond calibration window

Symptoms

• Check-engine light
• A/C may not cool
• A/C may switch on and off unexpectedly

How to diagnose it

1. Save freeze-frame data and watch live sensor B pressure as the A/C is commanded on and off to see whether the reading changes plausibly.
2. Inspect sensor B and its connector and wiring for damage, contamination, corrosion, or a loose connection.
3. Compare sensor B's reported pressure with an approved A/C service-equipment reading under the same conditions.
4. Have refrigerant charge checked using the manufacturer's procedure; do not infer charge from the code alone.
5. If charge and wiring are sound, test sensor B output and response against the manufacturer's specification.

Common fixes

• Repair loose, corroded, or damaged sensor B wiring and connector contacts.
• Correct a verified low refrigerant charge after checking for leaks.
• Replace sensor B if its response is contaminated, aged, or outside the manufacturer's specification.
• Clear the code and confirm sensor B tracks pressure normally during an A/C operating check.

Can I keep driving?

Driving is generally possible if the engine and vehicle operate normally, but A/C cooling may be weak or intermittent. Do not rely on the A/C to demist windows until it works consistently.