Hope this helps.
Purchased a used 2013 Jetta TDI with 65k miles. Filled up with diesel from top supplier & added Kleen Diesel octane booster/cleaner/additive. Power & MPG increased significantly. 1 month later, engine light comes on. DPF needs replacing...
Was told I have to wait at least one (1) month for parts to arrive! Dealership told me it’s ok to drive. MPG gradually started to drop along with power. During heat wave in July, vehicle shut off at traffic light. Started back up but felt weird. Called dealership, told them what happened & all of a sudden, the parts arrived! Certified preowned warranty covered the cost of repairs & runs like new!
Comments from dealership repair invoice: “69493 MIL is on and vehicle does lack performance. Excessive soot in tail pipe and egr filter pipe. Replaced dpf, egr filter pipe, and all associated hardware. Reset dpf adaptations and soot level. Vehicle now performs as it should.”