Mazda2006–2011

BT-50 2.5 Turbo: Common faults & known problems

Common faults & known problems

15 known faults documented in workshop bulletins. Of these, 11 concern the engine and fuel system and one the electrical and ignition. Symptoms, causes, repair steps and part numbers are shown where supplied.

Technical specifications

Engine & fuel system

11 documented faults — symptoms, causes and workshop fixes.

Engine overheating

Affects All models with Diesel engines.

Symptoms

Coolant loss with no signs of coolant leak.

Cause

Exhaust gas recirculation (EGR) cooler internally damaged.

Repair

Replace exhaust gas recirculation (EGR) cooler.

Data: Motorwise Workshop. Bulletin 1.

Failure to start

Affects All models with Diesel engines.Fit new part

Symptoms

Trouble code related to fuel rail pressure (FRP) sensor stored in fault memory.

Cause

Fuel rail pressure (FRP) control valve stuck or sticking.

Repair

Fit new fuel rail pressure (FRP) control valve.

Data: Motorwise Workshop. Bulletin 2.

Failure to start. No trouble codes stored in fault memory

Affects All models with Diesel engines.

Cause

Engine wiring harness broken near engine control module (ECM).

Repair

Check engine wiring harness for damage. Repair/replace component(s) as necessary.

Data: Motorwise Workshop. Bulletin 3.

Engine coolant contaminated with engine oil

Internal failure of engine oil cooler. Fix: clean and lubricate.

Overview

Affects: All models with Diesel engines.
Remedy: Clean & lubricate

Repair steps

Renew engine oil cooler.
Change oil and filter.
Thoroughly clean out engine coolant system.

Data: Motorwise Workshop. Bulletin 4.

Failure to start

Overview

Affects: All models with Diesel engines.
Remedy: Adjust & tighten

Symptoms

Various trouble codes stored in engine control module (ECM) fault memory.

Cause

Earth point corroded or loose.

Repair

Locate and check condition of earth point: Earth point adjacent to battery. Earth point adjacent to injector wiring harness on cylinder head.
Clean/tighten earth point.

Data: Motorwise Workshop. Bulletin 5.

Engine malfunction indicator lamp (MIL) illuminated. Trouble code stored: P0191

Affects All models with Diesel engines.P0191Fit new part

Symptoms

Poor engine running.

Cause

Fuel pressure sensor faulty.

Repair

Fit new fuel pressure sensor.

Data: Motorwise Workshop. Bulletin 6.

Engine cranks but fails to start

Affects All models with Diesel engines.

Cause

Poor connection between fuel injector and harness multi-plug.

Repair

Check electrical connection between fuel injector and harness multi-plug terminals. Repair as necessary.

Data: Motorwise Workshop. Bulletin 8.

Engine overheating, particularly in slow moving traffic

Affects All models.

Cause

Cooling fan viscous coupling faulty.

Repair

Replace cooling fan viscous coupling.

Data: Motorwise Workshop. Bulletin 9.

Engine will not start

Overview

Affects: All models with Diesel engines.
Fault codes: P0093
Remedy: Fit new part

Symptoms

Trouble code stored in engine control module (ECM) fault memory: P0093.

Cause

Fuel pressure relief valve faulty.

Repair

Fit new fuel pressure relief valve.
Access ECM fault memory and erase trouble code.

Data: Motorwise Workshop. Bulletin 13.

Engine speed will not increase above 2100rpm

Affects All models with Diesel engines, →2018.Fit new part

Cause

Fuel temperature sensor faulty.

Repair

Fit new fuel temperature sensor.

Data: Motorwise Workshop. Bulletin 14.

Engine will crank but not start

Fuel injector displaced due to retaining bolt broken. Fix: clean and lubricate.

Overview

Affects: All models with Diesel engines.
Fault codes: P0301
Remedy: Clean & lubricate

Symptoms

Lack of engine power. Trouble code stored in engine control module (ECM) fault memory: P0301.

Repair steps

Thoroughly clean threads in cylinder head. Repair/replace components as necessary.
Replace fuel injector retaining bolt.
Erase trouble codes from ECM fault memory.

Data: Motorwise Workshop. Bulletin 15.

Electrical & ignition

1 documented fault — symptoms, causes and workshop fixes.

SRS warning lamp illuminated. Trouble code stored: B1342

SRS control module faulty. Fix: fit a new part.

Overview

Affects: All models.
Fault codes: B1342
Remedy: Fit new part

Repair steps

Carry out electrical, mechanical and component tests (as applicable) to eliminate any other possible cause(s).
If no fault(s) found: Fit new SRS control module.
If SRS control module replaced: Renew side airbag crash sensor(s).

Data: Motorwise Workshop. Bulletin 10.

Brakes

1 documented fault — symptoms, causes and workshop fixes.

ABS/ESP warning lamp illuminated

Affects All models.C1950Fit new part

Symptoms

Trouble code stored in ABS control module fault memory: C1950.

Cause

G-force sensor faulty.

Repair

Fit new G-force sensor.

Data: Motorwise Workshop. Bulletin 7.

Clutch & gearbox

1 documented fault — symptoms, causes and workshop fixes.

Four wheel drive does not engage

Affects All models with four wheel drive.

Symptoms

Four wheel drive low range warning lamp illuminated. Speedometer erratic.

Cause

Transmission wiring harness damaged.

Repair

Check transmission wiring harness for damage and repair/replace as necessary.

Data: Motorwise Workshop. Bulletin 12.

Other

1 documented fault — symptoms, causes and workshop fixes.

Radiator leaks

Overview

Affects: All models.

Cause

Cooling fan viscous coupling faulty causing excessive pressure in cooling system.

Repair

Replace cooling fan viscous coupling.
Replace radiator as necessary.

Data: Motorwise Workshop. Bulletin 11.

Glossary

Technical terms used in this guide.

ECM: Engine control module — the electronic unit that manages the engine
ABS: Anti-lock braking system — stops the wheels locking under hard braking
EGR: Exhaust gas recirculation — feeds some exhaust gas back into the intake to cut emissions
Fuel Rail: The pipe that distributes high-pressure fuel to the injectors
Trouble Codes: Standardised fault codes stored by the engine control module, read with a diagnostic tool
SRS: Supplementary restraint system — the airbags and seat-belt pretensioners
Control Module: A control unit for one of the vehicle's systems (engine, gearbox, brakes, body, and so on)
Crash Sensor: A sensor that detects an impact and can trigger the alarm or airbags
Fault Memory: The list of stored trouble codes in a control module
Fuel Pressure Relief Valve: A valve that dumps excess fuel pressure back to the tank
Multi-Plug: A multi-pin electrical connector on a wiring harness
Trouble Code: A standardised fault code stored by a control module, read with a diagnostic tool
Viscous Coupling: A fluid coupling that automatically sends drive to an axle when the other starts to slip
Wiring Harness: The bundled cables that carry power and signals around the vehicle
Earth: An electrical ground connection back to the battery or body
Recirculation: Air-conditioning mode that recirculates cabin air instead of drawing in outside air

Frequently asked questions

What are the common faults with the Mazda BT-50 2.5 Turbo?

This guide contains 15 workshop bulletins for the Mazda BT-50 2.5 Turbo. Of these, 11 concern the engine and fuel system and one the electrical and ignition. Symptoms, causes, repair steps and part numbers are shown where supplied.

Does every Mazda BT-50 2.5 Turbo have these faults?

No. These are patterns documented across the model by workshops, not predictions for an individual vehicle. Where a fault applies only to certain vehicles or VIN ranges, that is listed with the fault.

Can I check for Mazda BT-50 2.5 Turbo faults myself?

Many of them. The documented symptoms can be seen, heard or felt during a test drive.