Exhaust problem on Renault Laguna Diesel

Start by checking the fuel injectors for any signs of clogging or leaks, as these can trigger the 'injection failure' message. Also, inspect the exhaust system for any visible damage or leaks, particularly around the catalytic converter and DPF (Diesel Particulate Filter). If you're unsure or the issue persists, it's best to have a professional mechanic take a look, as driving with a potential exhaust issue can be unsafe. Let us know how it goes or if you have further questions!