Seat Ibiza 1.0 TGI Mk5

CNG vehicles in the EU are subject to mandatory periodic tank inspections. In Germany the gas system test (Gasanlagenpruefung, GAP) is required every 2 years and inspection-type vary by country. Costs typically run 100-200 euros per inspection at a certified workshop. The three steel tanks themselves have a 20-year fixed service life and must be replaced when this expires, regardless of condition. Skipping an inspection invalidates the registration and insurance, and means automatic failure at the next periodic technical inspection (TUEV/MOT/APK). Always ask to see the inspection sticker and the documentation before purchase. This is not really a defect, but it is a recurring ownership cost that petrol Ibizas do not have.

The CNG system uses a high-pressure regulator that reduces tank pressure (up to 200 bar) to the working pressure of the gas injectors. Over time the diaphragm and seals inside can wear, leading to symptoms ranging from a check engine light and automatic switch to petrol mode, to audible hissing near the engine bay (gas leak). Replacement at a Seat or specialist CNG workshop costs 400-700 euros for the part plus 1-2 hours labor. Failures are not extremely common but they do occur, particularly on cars with high CNG mileage. The car remains drivable on the petrol back-up tank, but the 9-litre tank limits range to roughly 150 km.

The 1.0 TGI uses a separate set of gas injectors mounted in the intake manifold. Over time these can accumulate residues from the CNG (oil carryover from compression stations, moisture, sulphur compounds) leading to misfires, rough idle on CNG, or the car refusing to switch from petrol to gas. Cleaning or replacement of the gas rail injectors costs 200-450 euros at an independent CNG specialist. Quality of CNG varies significantly between stations and countries, and cars regularly fuelled at lower-quality stations show this issue earlier. Most affected cars have done significant mileage primarily on CNG.

Same widely reported issue as on the rest of the Ibiza Mk5 range, particularly pre-2021 models. The infotainment system can freeze mid-use, enter a reboot loop, or lose Bluetooth and Apple CarPlay connectivity. Seat issued software updates that resolve most cases. A dealer flash costs around 50-100 euros outside warranty. In rare cases the control unit in the glovebox (not the screen itself) needs replacement, costing 250-400 euros with a refurbished unit. Post-facelift cars (2021+) are noticeably less affected.

The wiring harness that passes through the rubber boot between the door and the body can chafe and break over time, particularly on the driver's door. Symptoms include the electric window stopping mid-travel, intermittent central locking failures, or door-related warning lights. Parts cost around 20-50 euros, with 1-2 hours of labor at an auto electrician. Total repair typically runs 100-350 euros depending on how many wires are affected.

Same coil-on-plug system as the rest of the EA211 family. CNG combustion runs slightly hotter than petrol, which can shorten coil life modestly. Symptoms include rough idle, misfires (very noticeable on a three-cylinder), and a check engine light. Each coil costs 25-45 euros aftermarket or 50-70 euros OEM and can be swapped quickly. Total repair at a workshop runs 100-300 euros depending on how many coils need replacing. Spark plugs should be replaced at the same time and CNG operation typically uses gas-specific plugs with a shorter service interval (every 30,000-60,000 km depending on driving).