ITV diesel Euro 5/6 with high opacity: failed and how to pass it at Zamule

You've passed the ITV with your diesel car and it failed due to high opacityIt's one of the most common rejections we see when vehicles arrive at our workshop. And for most, there's a solution without you having to replace your DPF or catalytic converter.

We explain what the ITV measures, what causes high opacity, and how we solve it at Zamule Cars Palma de Mallorca with a protocol tested on hundreds of cars.

What does the ITV measure and what is the legal limit

The ITV measures the exhaust smoke opacity with an approved opacimeter during a free acceleration test. The current legal limits in Spain:

• Euro 6 (registrations > Sep 2015): the 0.70 m limit?
• Euro 5 (Jul 2009 to Aug 2015): the 1.50 m limit?
• Older cars: more permissive limits based on registration

When a car reaches 2-7 m? (which is normal for a saturated DPF or a clogged intake) the ITV is automatically failed.

Most common causes we see in the workshop:

• Saturated or inefficient DPF
• EGR valve stuck due to carbon build-up (constantly admits dirty gases)
• Leaky turbo or oil
• Injectors that aren't atomizing properly
• Faulty lambda probe or NOx sensor
• Oil heavily diluted with diesel (dirty combustion)
• Heavy soot buildup from urban use

If you're going to do your ITV soon, check out these symptoms

If your car has one or more of these symptoms, there's a serious risk of failing:

• Grey or black smoke when accelerating
• Loss of power
• Yellow engine light
• Recurring emergency mode
• High fuel consumption
• Smell of burnt diesel
• Oil above maximum level (dilution)
• Frequent short urban trips
• No decarbonization in the last 80,000-100,000 km

Zamule pre-ITV diesel protocol 95% approval rate

When a client arrives with a failed ITV or suspects they won't pass, this is our protocol:

1. OEM Diagnostic + fault code reading + real opacity measurement with approved opacimeter
2. Identification of the real cause (DPF, EGR, turbo, injectors, oil)
3. Hydrogen decarbonisation Intensive (2h, 180€ + VAT) - resolves mild and medium cases
4. If the DPF is heavily saturated: Thorough DPF cleaning professional (from 280?)
5. If the intake is carbonized: disassembly + ultrasound (from 580 ? for commercial / 980 ? for high-end)
6. Oil change + filter if diluted
7. Final verification with approved opacimeter in our workshop before its ITV inspection
8. Written report with before/after values

We guarantee opacity below the limit, or we repeat the work free of charge. Success rate at Zamule: 95% pass rate on first attempt ITV.

Prevention & how to avoid this problem again

• Annual hydrogen engine cleaning (120-180 ? + VAT the best insurance)
• Oil change every 15,000 km maximum with DPF spec oil (low-SAPS)
• Fuel filter every 30,000-40,000 km
• Mixed driving: at least 1 long journey (45+ min) per week
• Air filter every 30,000 km
• Refuel at high-turnover petrol stations
• DPF cleaning every 100,000 km as maintenance
• If you mainly drive in the city, come for a pre-ITV check 2-3 weeks before the due date.

Conclusion act today, save tomorrow

Passing the ITV with correct opacity is perfectly possible without having to replace the entire DPF. The key: correct diagnosis + professional work + verification with an opacimeter. At Zamule Cars, we guarantee results, or we'll do it again.

More about DPF cleaning · Hydrogen engine decarbonization.