Fault code P1540 – a step-by-step guide to diagnosing and fixing it

Error code P1540 is displayed and the check engine light is on - what does this mean?

The DTC P1540 is a manufacturer-specific fault code that is recognized by the OBD system and typically signals problems with the exhaust gas recirculation (EGR) or turbocharger system. This code can have different meanings for different vehicle brands, but usually refers to pressure sensors or actuators in the engine management system.

What causes can this error code have?

• Defective EGR servomotor or turbocharger servomotor
• Damaged pressure sensor in the intake tract
• Blocked or leaking vacuum lines
• Defective cable connections to the servomotor
• Contaminated EGR valves or turbocharger components
• Faulty engine control unit software
• Mechanical blockage of the servomotors
• Corroded plug connections

What symptoms occur in parallel with error code P1540?

• Loss of power: Significantly reduced engine power, especially at higher engine speeds
• Uneven idling: Engine runs unevenly at idle speed
• Starting problems: Delayed starting or difficult starting of the engine
• Increased fuel consumption: Noticeably higher consumption due to inefficient combustion
• Black smoke: Dark exhaust fumes from the exhaust, especially when accelerating
• Emergency running program: Vehicle switches to emergency mode with limited power

How can the problem with error code P1540 be rectified?

• The repair requires a systematic diagnosis, as various components may be affected.
• Clean the EGR system: Completely clean the EGR valve and lines with special cleaner, then perform a function test
• Replace the servomotor: Replace defective EGR or turbocharger servomotor with original part and have it recalibrated
• Check and replace pressure sensor: Test boost pressure or intake manifold pressure sensor for function and replace if defective
• Replace vacuum lines: Check all vacuum lines for cracks and leaks and replace damaged hoses
• Repair wiring harness: Check electrical connections to the servomotor for continuity and insulation faults, repair defective cables
• Carry out software update: Update the engine control unit to the latest software version and reset the basic settings