P2527: Vacuum Reservoir Pressure Sensor Circuit Low

What it means

The vacuum reservoir pressure sensor circuit signal is below the expected limit. The code does not identify the cause or the vehicle's response.

At a glance

• Usually lights the check-engine light

How it works

The vacuum reservoir pressure sensor reports pressure in a vacuum reservoir used by a vehicle system. The control module monitors its signal circuit and sets P2527 when the signal falls below the expected limit; a grounded signal wire or missing sensor reference can cause this low reading.

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

• Vacuum-assisted functions may be reduced or inconsistent
• A related warning light may appear

How to diagnose it

1. Record freeze-frame data and check live reservoir pressure sensor data for a low or implausible signal.
2. Inspect the sensor connector and wiring for corrosion, loose pins, chafing, or a signal wire touching ground.
3. Using the wiring diagram, check the sensor reference, ground, and signal circuits against the manufacturer's specification.
4. With the circuit isolated as directed by the manufacturer, test the signal wire for a short to ground and check continuity.
5. If the wiring and reference pass, test the reservoir pressure sensor and compare its output with the manufacturer's specification.

Common fixes

• Repair a signal wire chafed through to ground.
• Clean or repair corroded or loose sensor connector terminals.
• Repair a missing reference supply or damaged sensor wiring.
• Replace the pressure sensor if its output remains low with a sound circuit.

Can I keep driving?

Drive cautiously until you know which system uses the vacuum reservoir, since a vacuum-assisted function may be reduced or inconsistent. If braking assistance or another safety-related function feels different, stop driving and have the vehicle checked.