VW Golf Hybrid Struggles with Injection System Issues

Having some experience with hybrid systems, I encountered similar symptoms on my 2021 VW Passat Hybrid. The issues you describe match what I experienced, particularly the increased fuel consumption and reduced power output. The maintenance inspection revealed a faulty cable connection at one of the fuel injection sensors. The system was triggering error codes due to inconsistent signals, causing the engine management to run in a conservative safety mode. This explains both the power reduction and higher fuel consumption. My repair cost was 95€, covering diagnostic work and fixing the loose connection. The workshop performed a thorough check of the entire fuel injection system and ran multiple tests to ensure everything was working correctly after the repair. Before offering more specific advice, could you share: Current mileage on your Golf, Whether you have any warning lights on the dashboard, When these symptoms first appeared, If the problems occur more during cold or warm engine conditions, Whether the check engine light is steady or flashing This information would help determine if your issue matches what I experienced with the sensor connection or if it might be related to another part of the fuel system.

At 15955km and following my last service two weeks ago, I think I can add some relevant details to help diagnose this. The check engine light started flashing intermittently, particularly during cold starts. The performance issues become more noticeable when the engine is cold, and the petrol consumption increase is most evident during city driving. The air temperature sensor shows normal readings, but I notice the engine struggles more on humid days. Yesterday, the power dropped significantly during acceleration, accompanied by white smoke from the exhaust. No other warning lights are present on the dashboard besides the occasional check engine flash. These symptoms began appearing gradually over the past three weeks, though the smoke is a new development within the last few days. This timing suggests the problem might be progressive rather than a sudden failure.

Thanks for providing those additional details, they help confirm my initial suspicions about the injection system. After the similar issues with my Passat Hybrid, the white smoke and flashing check engine light strongly suggest there could be a fuel mixture problem. On my vehicle, the intermittent flashing specifically pointed to fuel injection timing issues. The system was getting incorrect air-fuel mixture readings, causing incomplete combustion, especially noticeable during cold starts just like youre experiencing. The appearance of white smoke combined with higher fuel consumption points toward possible coolant entering the combustion chamber, which wasnt my initial problem but needs investigation. In my case, the faulty sensor connection was creating similar symptoms, but your situation sounds more serious, possibly involving: A cracked cylinder head, Failed fuel injector seals, Faulty engine control unit signals Given the low mileage and recent service, I recommend getting the car checked immediately while under warranty. A proper diagnosis using manufacturer diagnostic equipment will be crucial. The progressive nature of your symptoms differs from my sensor issue, which had more consistent symptoms throughout. Would you be able to specify if the smoke has a sweet smell? This detail would help determine if coolant is indeed entering the combustion system.

Thanks to everyone who contributed insights about my Golf's issues. After reading about the similar Passat case and analyzing the symptoms together, I think taking immediate action under warranty is the best path forward. The mention of coolant potentially entering the combustion chamber definitely concerns me, especially given the white smoke and increased fuel consumption. My engine actually does emit a slightly sweet smell with the smoke, which seems to confirm the coolant theory. This detail, combined with the flashing check engine light and cold start problems, makes me think this could be more serious than just a sensor issue. The fact that these symptoms have progressively worsened over three weeks, rather than appearing suddenly like a simple sensor fault, suggests something might be deteriorating in the system. I will schedule an urgent warranty inspection and specifically request a thorough check of the fuel injection system, cylinder head, and coolant circulation. The service center should be able to run complete diagnostics to pinpoint whether we are dealing with mechanical damage or control unit issues. I will update this thread once I have more information from the inspection.