Fault code P0473 – a step-by-step guide to diagnosing and fixing it

Error code P0473 is displayed and the check engine light is on - what does this mean?

The OBD system detects a fault in the exhaust pressure sensor circuit, specifically a signal that is too high (high input). This DTC P0473 relates to the exhaust gas aftertreatment system and may have slightly different names for different manufacturers, but always refers to the exhaust gas pressure sensor.

What causes can this error code have?

• Defective exhaust gas pressure sensor
• Damaged cable connections to the sensor
• Corroded or loose plug connections
• Short circuit in the sensor wiring
• Blocked pressure lines to the sensor
• Defective engine control unit (ECU)
• Mechanical damage to the sensor mounting area

Which symptoms occur in parallel with fault code P0473?

• Check engine light: Continuously illuminated warning light in the dashboard
• Loss of power: Reduced engine power, especially under load
• Increased emission values: Poorer emission values during the main inspection
• Uneven idling: Engine runs unevenly at idle speed
• Regeneration problems: Faulty DPF regeneration in diesel vehicles
• Emergency running program: Vehicle switches to emergency running mode

How can the problem with error code P0473 be rectified?

• The repair requires a systematic diagnosis of the exhaust pressure sensor components.
• Replace the sensor: Replace the defective exhaust pressure sensor completely, clean the connections and fit the new sensor professionally
• Repair wiring harness: Locate damaged cables, repair defective areas or replace entire wiring harness and insulate all connections
• Repair plug connections: Clean corroded contacts, replace damaged plugs and treat connections with contact spray
• Check and clean pressure lines: Blow through clogged hoses, replace damaged lines and ensure correct installation
• Diagnose the engine control unit: Carry out ECU function test, replace control unit or have it repaired if defective