Mazda CX3 Diesel Troubleshooting: Persistent Pre-Glow Light, Black Smoke, and Possible DPF Regeneration Failure

Hey there, sounds like you're in a bit of a bind. Now I'm no expert, but I've got some experience under my hood. Dealt with something similar in my 2018 Mazda CX5 Diesel. Smoke, trouble starting, and guzzling fuel sounds all too familiar. Turned out to be a dodgy glow plug, just like your guess. My workshop took it in, ran some checks to confirm it was the glow plug at fault and yep, defective due to wear. They replaced it and soon enough, my ol' car was purring again. Cost me a whopping €560, not fun, but had to be done. Could you let me know how many miles your CX3 has clocked? Also, any recent services or part replacements you've carried out? It'll help me fine-tune my "not-quite-expert" advice for you. Hang in there!

Hey, appreciate you taking the time to share your experience. My CX3's racked up a good 213621 km so far. Latest service was a while back, I might be overdue, yup, need to check that out. Nope, haven't replaced any parts recently. Was hoping to make it through this year without any surprises, but my car clearly thought otherwise! Let's see where this goes. Cheers!

Hey, that's quite a few km there on your CX3. With this kind of mileage, a worn out glow plug could very well be the culprit. The failure to start, poor fuel economy, and the check engine light can indicate a faulty glow plug. With the mileage you've got, the old glow plug may have just given up on life. Remember my €560 burn? Yep, mostly it was for the glow plug replacement and diagnostic test and a few quid for wrestling with the DPF regeneration. The black smoke though, could be due to incomplete DPF regeneration. You might want to get that checked immediately, especially as your pre-glow light is constantly on. Scheduling a service soon would be a good idea too. Just keep in mind, meticulous and timely maintenance can prolong the life of parts like your glow plug and prevent these surprise hitches. Hope it works out for you. Stay strong and safe on the road!

Cheers for the advice, you've been a big help! Definitely getting my car booked in for a check up this week itself. Fingers crossed it's not too pricey. But hey, safety first, right? Plus I want to keep my ride running as smoothly as possible. Thanks again and safe driving to you too!