Mazda CX-8: 2.2 SkyActiv-D DPF clogging and oil dilution on short trips
2.2 SkyActiv-D DPF clogging and oil dilution on short trips is a common engine fault on the Mazda CX-8 on the 2018–2023 cars, and we rate it major. Putting it right costs $800 to $2,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 12 documented faults on the Mazda CX-8.
- Vehicle
- Mazda CX-8
- Engine
- 2.2L
- Years
- 2018–2023
- Fuel
- diesel
- System
- Engine
What you are looking at
No photograph available
What goes wrong
The 2.2 diesel's particulate filter (DPF) relies on regular highway runs to burn off soot, and cars used mostly for short city trips clog the DPF, trigger warning lights and limp mode, and dump unburnt diesel into the engine oil so the oil level climbs. Over-full, diesel-diluted oil can damage the engine. This is the single most important thing to check on a used diesel CX-8, and it is really a wrong-use problem.
What you would notice
- DPF or check-engine warning light
- Loss of power / limp mode
- Engine oil level rising and smelling of diesel
How to check it
Where to look. Diesel particulate filter in the exhaust; engine oil
Ask how the car has been used - lots of short city trips is the danger.
Pull the dipstick and check the oil is not over the full mark or smelling of diesel.
On the drive check it makes full power.
Ask if the DPF has ever been forcibly regenerated or replaced.
What it costs to put right
$800 to $2,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.
Ask the seller
- “Is it used for short trips or regular longer runs?”
- “Has the DPF ever clogged, been regenerated or replaced?”
Now check the Mazda CX-8 you are actually looking at
Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.
Where this comes from
- Whirlpool Australia forum 'CX8 Diesel DPF problems' thread
- Mazda6Club 'Things To Know Before Buying SkyActiv 2.2D' thread
Mazda CX-8 buyer questions
Is 2.2 skyactiv-d dpf clogging and oil dilution on short trips serious on a Mazda CX-8?
We rate it major and common on the Mazda CX-8. The 2.2 diesel's particulate filter (DPF) relies on regular highway runs to burn off soot, and cars used mostly for short city trips clog the DPF, trigger warning lights and limp mode, and dump unburnt diesel into the engine oil so the oil level climbs. Over-full, diesel-diluted oil can damage the engine. This is the single most important thing to check on a used diesel CX-8, and it is really a wrong-use problem.
How much does it cost to fix on a Mazda CX-8?
$800 to $2,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.
Which Mazda CX-8 years are affected?
Our research records this fault on the 2018–2023 Mazda CX-8. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.
How do I check for it before I buy?
Ask how the car has been used - lots of short city trips is the danger. Pull the dipstick and check the oil is not over the full mark or smelling of diesel. On the drive check it makes full power. Ask if the DPF has ever been forcibly regenerated or replaced. Look here: Diesel particulate filter in the exhaust; engine oil