Failed EGR boost sensor (pressure sensor) itself; Damaged or disconnected electrical connector at the boost sensor; Cracked, clogged, or disconnected vacuum hose between the sensor and the EGR system; Wiring harness damage such as chafed wires or corroded terminals; Carbon buildup blocking the pressure port or passage to the sensor; Faulty EGR valve or solenoid affecting the pressure signal; Rarely, a PCM (powertrain control module) internal fault

DTC codes / Mazda codes / P1195

P1195 · MazdaEGR Boost Sensor Circuit

Q: What does code P1195 mean?

EGR Boost Sensor Circuit. P1195 on Mazda vehicles means the powertrain control module has detected a fault in the electrical circuit for the EGR (exhaust gas recirculation) boost sensor, which monitors pressure in the EGR system. The computer compares the sensor signal against expected values and flags the code when the voltage or pressure reading falls outside the normal range.

P1195 on Mazda vehicles means the powertrain control module has detected a fault in the electrical circuit for the EGR (exhaust gas recirculation) boost sensor, which monitors pressure in the EGR system. The computer compares the sensor signal against expected values and flags the code when the voltage or pressure reading falls outside the normal range.

SystemPowertrain

Code typeMazda specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or stumbling when the engine is cold
Slight hesitation or surge during light acceleration
Poor fuel economy in some cases
Failed emissions test due to incomplete EGR monitor
In rare cases, a noticeable loss of power or engine ping under load

Common causes, most likely first

Failed EGR boost sensor (pressure sensor) itself
Damaged or disconnected electrical connector at the boost sensor
Cracked, clogged, or disconnected vacuum hose between the sensor and the EGR system
Wiring harness damage such as chafed wires or corroded terminals
Carbon buildup blocking the pressure port or passage to the sensor
Faulty EGR valve or solenoid affecting the pressure signal
Rarely, a PCM (powertrain control module) internal fault

How to diagnose and fix it

Inspect the EGR boost sensor connector and wiring for looseness, corrosion, or damage
Check all vacuum hoses connected to the sensor for cracks, clogs, or disconnection
Test the sensor's reference voltage and signal voltage with a multimeter and compare to Mazda specifications
Remove and clean the sensor's pressure port and passage of carbon deposits
Replace the EGR boost sensor if electrical tests confirm it is out of range
Clear the code and perform a drive cycle to verify the repair
If the code persists, diagnose the EGR valve and related circuits

What Mazda techs check before replacing the sensor

A clogged EGR passage or carbon-fouled pressure port often mimics a failed boost sensor, so clean the port before condemning the sensor.
The boost sensor on many Mazdas is mounted on the firewall or intake and its vacuum hose can crack invisibly, causing a signal that looks like sensor failure.
P1195 can set intermittently due to a loose connector that only loses contact during engine vibration, so wiggle-test the harness while watching live data.
A faulty EGR solenoid or stuck EGR valve can skew the pressure reading and set P1195 even when the sensor itself is good.
Do not overlook a weak battery or charging system, as low voltage can cause false sensor codes on Mazda PCMs.

Can I keep driving with P1195?

You can usually continue driving with P1195 because it rarely causes immediate drivability or safety issues, but avoid long-term neglect since it can affect emissions and fuel economy. Have the fault diagnosed soon, especially if you notice rough running or hesitation.

Tools that help

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