Faulty vacuum reservoir pressure sensor; Damaged or disconnected vacuum hose between the reservoir and the sensor; Leaking or cracked vacuum reservoir tank; Corroded or damaged electrical connector at the sensor; Open or shorted wire in the sensor circuit; Failed PCM (rare but possible)

DTC codes / P25xx · Vehicle speed, idle control and auxiliary inputs / P2525

P2525Vacuum Reservoir Pressure Sensor Circuit

Q: What does code P2525 mean?

Vacuum Reservoir Pressure Sensor Circuit. P2525 indicates that the powertrain control module (PCM) has detected an abnormal signal from the vacuum reservoir pressure sensor circuit, which monitors the pressure inside the vacuum reservoir used by the engine's intake manifold vacuum system. The computer compares the sensor's voltage output to expected values and sets this code when the signal falls outside the normal range or is inconsistent with other engine data.

P2525 indicates that the powertrain control module (PCM) has detected an abnormal signal from the vacuum reservoir pressure sensor circuit, which monitors the pressure inside the vacuum reservoir used by the engine's intake manifold vacuum system. The computer compares the sensor's voltage output to expected values and sets this code when the signal falls outside the normal range or is inconsistent with other engine data.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illumination of the check engine light (malfunction indicator lamp) on the dashboard
Often no symptoms besides the warning light, especially if the vacuum reservoir is not critical for immediate engine operation
Reduced engine performance or hesitation under acceleration if the vacuum reservoir is not maintaining proper vacuum
Poor fuel economy or rough idle in some cases
Intermittent operation of vacuum-operated accessories such as HVAC blend doors or cruise control
Possible stalling or hard starting if the vacuum leak is severe

Common causes, most likely first

Faulty vacuum reservoir pressure sensor
Damaged or disconnected vacuum hose between the reservoir and the sensor
Leaking or cracked vacuum reservoir tank
Corroded or damaged electrical connector at the sensor
Open or shorted wire in the sensor circuit
Failed PCM (rare but possible)

How to diagnose and fix it

Inspect all vacuum hoses and connections for cracks, leaks, or disconnections; repair or replace as needed
Check the electrical connector at the vacuum reservoir pressure sensor for corrosion or loose pins; clean or repair
Test the sensor's reference voltage and signal voltage with a multimeter; compare to manufacturer specifications
Perform a vacuum leak test on the reservoir and associated components using a vacuum gauge or smoke machine
Replace the vacuum reservoir pressure sensor if testing indicates it is faulty
Repair any wiring issues in the sensor circuit (open, short, or high resistance)
Clear the diagnostic trouble codes and verify the repair by test-driving the vehicle and ensuring the code does not return

Don't overlook vacuum leaks before sensor replacement

A leaking vacuum reservoir or cracked hose is a common cause that is often missed because the sensor itself may test good; always perform a visual and vacuum leak inspection first.
The vacuum reservoir pressure sensor may share a circuit with other sensors, so a fault in a related component can set P2525 as a secondary code.
On some vehicles, the vacuum reservoir is integrated into the intake manifold or valve cover, making leaks harder to spot without a smoke test.
A faulty check valve in the vacuum line can cause the reservoir to lose vacuum, triggering the code without any sensor failure.
Intermittent P2525 codes can be caused by a loose connector that only loses contact under vibration; wiggle-test the harness while monitoring sensor data.

Can I keep driving with P2525?

The vehicle is generally safe to drive with P2525 set, but you may experience reduced performance or fuel economy. Avoid heavy acceleration or towing until the fault is repaired, and address the issue promptly to prevent potential damage to other vacuum-operated systems.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.