Boost leak from a split, loose or disconnected charge air hose, clamp or intercooler joint; Vacuum or pressure line to the boost control actuator or wastegate/vane control split, loose or blocked; Faulty boost pressure (MAP) sensor, or damaged wiring or connector to it; Turbocharger actuator, wastegate or variable vane mechanism stuck or worn (depends on engine); Boost control solenoid or its wiring faulty; Restricted air filter, intake or blocked exhaust flow reducing turbo output; Worn or damaged turbocharger with shaft play or damaged blades.

P1248

Turbo Boost Pressure Not Detected.

Ford
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
2: AreaFuel and air metering (injector circuit)
48: FaultThe specific fault in that area

What it means

P1248 on a Ford means the powertrain control module did not see the boost pressure it expected from the turbocharger. The actual boost reading from the sensor stayed too low, or showed no rise, compared with the target for the engine load and speed. The exact test and thresholds vary by engine, so check the model-specific information.

Symptoms

Noticeable loss of power, especially under acceleration
Engine management light on
Car may go into a reduced power (limp) mode
Little or no boost shown on live data when accelerating
Whistling, hissing or a change in turbo noise
Black or blue smoke from the exhaust on some engines

Possible causes

Boost leak from a split, loose or disconnected charge air hose, clamp or intercooler jointlikely
Vacuum or pressure line to the boost control actuator or wastegate/vane control split, loose or blockedlikely
Faulty boost pressure (MAP) sensor, or damaged wiring or connector to itpossible
Turbocharger actuator, wastegate or variable vane mechanism stuck or worn (depends on engine)possible
Boost control solenoid or its wiring faultypossible
Restricted air filter, intake or blocked exhaust flow reducing turbo outputpossible
Worn or damaged turbocharger with shaft play or damaged bladesrare

How to diagnose

Read all stored and pending codes and the freeze frame data, and note engine load, speed and boost at the time the fault set
Visually inspect the air filter, intake pipework, charge air hoses, clamps and intercooler for splits, oil residue, looseness or damage
Check the wiring and connectors of the boost pressure sensor and boost control solenoid for damage, corrosion or poor contact
Inspect the vacuum or pressure hoses to the turbo actuator for cracks, kinks and correct routing
Compare actual and target boost on live data during a safe road test, and check the sensor reads correctly with the engine off
Pressure test the charge air system for leaks, following the procedure for the specific engine
Test the boost control solenoid and actuator operation using bidirectional tests or the manufacturer's procedure
Check the turbo for shaft play, oil leaks and free movement of the wastegate or vanes, and check for exhaust restriction

How to fix

Replace or refit any split, loose or disconnected charge air hoses, clamps or leaking intercooler
Replace damaged vacuum or pressure lines to the turbo actuator
Repair the wiring or connectors, or replace the boost pressure sensor if it is faulty
Replace the boost control solenoid if it fails testing
Repair or replace the turbo actuator or turbocharger if the mechanism is stuck or worn
Replace a blocked air filter and clear any intake or exhaust restriction, then clear the code and road test

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but power will be reduced and it should be fixed soon. Avoid heavy loads and hard acceleration, and stop if you hear unusual turbo noises or see heavy smoke.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.