Worn or faulty throttle body position sensor, with one track out of range; Carbon build-up or sticking throttle plate preventing proper movement; Damaged wiring, corroded terminals or loose connector in the throttle sensor circuit; Faulty accelerator pedal position sensor giving signals that disagree with throttle position; Poor sensor reference voltage or earth supply, including a fault in a shared circuit; Faulty throttle motor or internal throttle body fault; Engine control unit internal fault.

P1574

Throttle Position Sensor Disagreement Between Sensors.

Mercury
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
5: AreaVehicle speed, idle control and auxiliary inputs
74: FaultThe specific fault in that area

What it means

On Mercury models, P1574 means the engine control unit has found that the throttle position sensor signals disagree with each other. Electronic throttle systems use two or more sensor tracks that should match within a set tolerance. When the readings drift apart, or do not match the pedal position request, the control unit sets the code and usually limits engine power as a precaution.

Symptoms

Engine warning light on
Reduced power or limp-home mode
Poor or delayed throttle response
Unstable or high idle
Engine hesitation or stalling at low speed
Throttle warning light, where fitted

Possible causes

Worn or faulty throttle body position sensor, with one track out of rangelikely
Carbon build-up or sticking throttle plate preventing proper movementlikely
Damaged wiring, corroded terminals or loose connector in the throttle sensor circuitpossible
Faulty accelerator pedal position sensor giving signals that disagree with throttle positionpossible
Poor sensor reference voltage or earth supply, including a fault in a shared circuitpossible
Faulty throttle motor or internal throttle body faultrare
Engine control unit internal faultrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting any accelerator pedal or throttle motor codes.
Inspect the throttle body connector, wiring and nearby harness for damage, chafing, corrosion, water ingress or loose pins.
Inspect the throttle plate and bore for carbon build-up or sticking, and check the intake for leaks or obstructions.
With live data, compare the throttle sensor tracks and the pedal sensor tracks while moving the pedal slowly through its full range, looking for dropouts, jumps or mismatches.
Check the sensor reference voltage and earth at the throttle body connector against the manufacturer's specification for your model.
Wiggle-test the harness with the ignition on while watching live data to find any intermittent fault.
Check the throttle body and pedal sensor resistance and signal circuits for continuity and shorts, following the model-specific wiring diagram.
Check for any applicable service bulletins or control unit software updates for your model and engine.

How to fix

Clean the throttle body if carbon is the cause, following the manufacturer's procedure, then carry out any throttle relearn that is required.
Replace the throttle body or its position sensor if the sensor tracks are faulty.
Repair or replace damaged wiring, terminals or connectors in the throttle sensor circuit.
Replace the accelerator pedal assembly if its sensor signals are faulty.
Update the control unit software only if an applicable bulletin identifies an outdated calibration as the cause.

Can I keep driving?

Medium severity

The car may be driven carefully a short distance if it runs normally, but power can be cut without warning, which is a hazard in traffic. Get it checked soon, and stop driving if it enters limp-home mode or stalls.

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