P2517: A/C Refrigerant Pressure Sensor B Circuit Low

What it means

The pressure sensor B circuit signal is below the expected limit. This can result from a circuit or sensor fault; the code does not identify the cause.

At a glance

• Usually lights the check-engine light

How it works

A/C refrigerant pressure sensor B sends a signal to the control module that represents refrigerant pressure. P2517 sets when that signal is below the expected limit, commonly because the signal is pulled low, the 5 V reference is missing, or the sensor B connector has excessive resistance.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Missing 5 V reference at the sensor
3. Connector pins corroded - high contact resistance

Symptoms

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

How to diagnose it

1. Record freeze-frame data and check live sensor B data for a low or fixed reading while noting whether other A/C pressure data is plausible.
2. Inspect sensor B's connector and harness for corrosion, loose terminals, chafing, or contact with ground.
3. Check the sensor B 5 V reference, ground, and signal circuits using the wiring diagram and manufacturer's procedure.
4. Test for a short to ground on the sensor B signal wire and check connector contact resistance against the manufacturer's specification.
5. If the circuits pass, test sensor B itself according to the manufacturer's specification.

Common fixes

• Repair a signal wire shorted to ground or damaged harness insulation.
• Restore the missing 5 V reference or repair its wiring fault.
• Clean or repair corroded, loose, or high-resistance connector terminals.
• Replace sensor B if it fails the manufacturer's test.

Can I keep driving?

You can generally drive if the vehicle runs normally, but the A/C may be disabled or cycle unexpectedly. Avoid depending on the A/C for demisting until the fault is corrected.