P2528: Vacuum Reservoir Pressure Sensor Circuit High

What it means

The vacuum reservoir pressure sensor circuit signal is above 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 P2528 when the signal rises above the expected limit; an open signal return or a signal wire shorted to reference voltage can produce this condition.

Common causes

Most likely first.

1. Signal wire shorted to reference voltage
2. Open signal return
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 high or implausible signal.
2. Inspect the sensor connector and wiring for corrosion, loose pins, damage, or a disconnected signal return.
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 reference voltage and check the signal return for an open.
5. If the wiring passes, test the reservoir pressure sensor and compare its output with the manufacturer's specification.

Common fixes

• Reconnect or repair an open sensor signal return.
• Repair a signal wire shorted to reference voltage.
• Clean or repair corroded or loose sensor connector terminals.
• Replace the pressure sensor if its signal remains high 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.