Fault code P1168 – a step-by-step guide to diagnosing and fixing it

Error code P1168 is displayed and the check engine light is on - what does this mean?

The DTC P1168 is a manufacturer-specific fault code that is recognized by the OBD/EOBD diagnostics and indicates a problem with the fuel system or the air supply. This trouble code mainly relates to the fuel-air mixture control and can have different meanings depending on the vehicle manufacturer, although it is often associated with the fuel pressure regulator or the intake manifold pressure control.

What causes can this error code have?

• Defective fuel pressure regulator
• Clogged fuel filter
• Damaged intake manifold pressure sensor
• Leaking vacuum hoses
• Defective fuel pump
• Dirty injection nozzles
• Faulty cable connections to the fuel system
• Defective engine control unit
• Clogged air filter
• Leaks in the intake tract

What symptoms occur in parallel with fault code P1168?

• Loss of engine power: Significantly reduced engine power while driving
• Uneven idling: Engine runs unevenly at idle speed
• Starting problems: Difficulty starting the engine, especially in cold weather
• Increased fuel consumption: Noticeable increase in fuel consumption
• Jerky engine: Uneven engine running at different engine speeds
• Stalling: Engine stalls while driving or idling
• Black smoke: Dark exhaust fumes from the exhaust pipe

How to fix the problem of fault code P1168?

• Repairing fault code P1168 requires a systematic diagnosis of the affected components.
• Replace the fuel pressure regulator and check the fuel pressure with a pressure gauge, replace the entire unit if there are deviations
• Replace the fuel filter and also check the fuel lines for blockages
• Test intake manifold pressure sensor and replace with original part if readings are incorrect
• Check all vacuum hoses for cracks and leaks, replace damaged hoses completely
• Test fuel pump for delivery pressure and delivery rate, replace if defective, including pre-filter
• Clean injection nozzles professionally or replace with new nozzles if heavily soiled
• Check the wiring harness to the fuel system for continuity and insulation damage, repair defective cables
• Read out engine control unit and carry out software update or replace control unit in the event of errors