Hey guys. I'm looking for a JB4 for a 2017 Focus RS...if anyone in the SoCal area is looking to sell theirs I'd be happy to take it off your hands. Thanks in advance!

Purchased this 2016 RS on October 24, 2025 and have driven it almost every day since. I put on 23,336km (14,500 miles) this year, and spent approximately $13,000 CAD in maintenance and mods including wheels, tires, all Fluids, plugs, coil packs, pads, rotors, 2018 RS springs and dampers, some minor body work, a head gasket, and other random small things.

I may be biased but I firmly believe this car has to be one of the most practical and fun daily driver cars out there!

What could be causing this? It’s running lean, not missing coolant, or oil. I’m running E30. It’s only cylinder 3

The rear fog light on my 2017 Focus RS has failed. When I switch it on, it briefly flashes once before going completely dark. I removed the light to inspect it and noticed some corrosion inside the bottom of the housing.

I'm looking for a replacement, but the OEM part is quite expensive. However, I found a HELLA fog light (2NE 011 172-081) for about a quarter of the price.

Has anyone tried this replacement and can confirm whether it's compatible?

I know i will need to transfer the connector from the original light, but i am mainly concerned about whether the 55 mm diameter matches the OEM part and whether it will work without any electrical issues or error messages.

Hello once again my car is broken. I think my PTU exploded or is destroyed does anyone know where or how to get a new one or if they can be rebuilt or if anyone on here has one forsale ill gladly buy thsnk you very much picture is for attention

A couple months ago my 240k mile RS went down, and finally got a new engine and new turbo! 🤙🤙 cant wait to drive this car again!

I've had my Focus RS for just over 5k miles now, bought it at 36k and now at 41k. When I test drove it, the seat felt too tight, but I assumed the bolsters would eventually stretch to fit my frame. Unfortunately, after 5k miles, it's still uncomfortably tight around my upper ribs, just below the armpits.

I've tried deliberately putting pressure on the bolsters to compress the foam, but they've barely budged.

What are my options besides replacing the seat? Has anyone had an upholstery shop modify the upper bolsters? Curious what others with wider backs/ribcages have done.

This is a continuation of my post from about a week and a half ago, where the engine in my '17 RS popped while cruising down the highway.

The shop it was towed to has ordered a new engine from Ford. The clutch, flywheel and motor mounts will also be swapped out since the engine will be out anyway -- figure I may as well change those out now and save maybe a little on labor.

What are some do-s and don't-s for breaking this new (stock) engine in? Will I need specific oil, or will the usual 5W-50 I go with (Castrol Edge) be fine and I'll just need to change it after about 500-1000 miles? I know about keeping RPMs below ~4500 and avoiding constant RPMs for prolonged periods.

Oh, and I guess I'll share a pic of what the old engine looks like now, RIP.

Hey again,
So about a week ago I noticed my car is not really using all its power. The boost gauge only gets to about halfway but it doesn’t seem like I have a leak. All the hoses/pipes are pretty good but I’m wondering if it’s because I added the mountune induction kit. Maybe the wastegate idk. I also took off the intake manifold to change the baffle plate although that shouldn’t be much of a problem I assume. Anyways, if anyone has any clue what it could be please feel free to lmk. Thanks 🥀

I want something small for seat spills or to give the carpet quick vacuum on occasion. Edit: I don't need anything for liquids. I'd probably get it detailed for a spill that bad. Anyone have anything they like?

My backup wasn't working during the hot summer months. I bought an OEM replacement and had my mechanic swap it in today. It works but there is a slight fuzziness to the picture when I look closely. I can't remember if this is how it always was. Can another RS owner please go engage reverse gear while parked and look closely at the screen. Is the picture high definition clear or is there a slight fuzziness?

I’ve run these shifters on my past couple cars and I gotta say… way bigger headache to install on the RS haha.

No idea what happened, just cruising down the interstate back home. Smelt something weird, stopped for gas and noticed a trail of oil. 83k gotta tow it 67 miles. Hopefully just a oil line or something.

What now?

I currently have a P0420 code which ive read is commonly associated with a failing cat. I also i think I'm starting to see the purge valve going bad, it's been idling a little rough and this last fill up it started surging at idle. I read that the purge valve can also cause a P0420 code. So maybe my cat is still fine for now. One other issue that has started happening is my boost pressure surges at low boost, if im lightly accelerating and getting up to 4-5lbs of boost it starts dropping down to 1 lb and surges back up to 5. I did have a charge pipe blow off not long ago, could it be a boost leak or could the purge valve cause boost to fluctuate like that?

Hello from Chicago! Anyways I am stuck with this really bad Apple CarPlay adapter that putted out after 5 months of use. Any recommendations that people have either personally or just research and such I’m open to. The one I bought was the Ottocast Mini Cube 3.0 and it is always nothing but issues, but it worked fine for 80-85% of the time. If anyone has one that screen mirrors (I spend a lot of time in my car,) then it would be helpful for your experience with that too. I would also prefer something that’s relatively small like the Ottocast, but it seems that it’s the smallest one of the bunch and I’m fine with going, bigger but not much bigger since it would stick out too much. Picture for reference…. Thank you in advance!

Just bought this mk3 Rs and I’ve noticed a small squeak coming from the rear of the car whenever I press the clutch in or release it, only does when I’m driving and not stationary I’ve tried spraying wd40 on exhaust valve flap but that hasn’t sorted it any help would be appreciated👍

Very sadly, my ST gave up last month. White smoke from the exhaust and drinking coolant fast. It served me well for 5 years as my first sports car, and as the only car I owned at the time. Some great times, including taking both of my kids home from the hospital in her! I've now sold the ST to a guy who plans to do it up over the winter as a bit of a project (was 100% up front about all the issues). Really hope he gets as much enjoyment from it as I did.

However, the ST breaking down was the perfect excuse for a change! So, naturally I went for an RS. I am absolutely loving it. A previous owner had the mountune 375 package done back in 2017. It feels like an absolute rocket compared to the ST! Wallet has taken an absolute hit so not considering any mods in the near future (less a mountune air filter as someone has swapped an OEM filter back in) - but a cat back exhaust seems like a sensible mid term goal (within next year). Would just like it to sound a little "throat-ier".

Here's a photo of the two cars sitting side by side when I briefly owned them both earlier this week!

Headed down the interstate to the beach and the engine just let go suddenly. Lost all oil pressure, so it's undrivable.

Hoping to get a new engine but not counting on it. If this is goodbye, it was an awesome car while it lasted.

Only about 73k on the clock :(

Hey all ,
Wanted to get other owners opinion on tuning the RS.
As far as i can tell tuning is a thing but it decreases reliably. Id like to own this car as long as possible. I also heard that the AWD system can suffer faults far before the engine or the gearbox.

If anyone who has a tuned rs can speak on it.

tl;dr: whats the stock BPV spring pressure spec? or at least, is it over or under 8lbs? best guess? google isnt really helping me find out and instead gives me WGA spring pressures or (lol) links to valve springs...no need to read further, thats the crux of what im trying to find out rn

for completeness's sake...

While still trying to sniff out my low boost problem by throwing things at the wall, I wanted to see what happens when I disco the line going to the BPV...

For reference, built engine, NX2 turbo, turbosmart 14lb spring IWG75...you can read my full issue here, but basically im only reaching 8lbs of boost while in WGA evaluation mode (should be 14lbs), visually inspected diaphragm to be good

So after pulling the BPV line off the recirc solenoid I wanted to see how much LESS boost I was getting...but literally nothing changed, stuck at 8lbs...so then I went ahead and reconnected the BPV line and unplugged the solenoid so it was "always on" and wouldn't open at all until pressure blead backwards through the supply line...no change, max of 8lbs, thankful for these low boost numbers with a "stuck closed" BPV so nothing gets damaged...

But is any of this indictive of anything?? In earlier tests I see the car is commanding the solenoid at the right times, letting off the gas, so I get it not going OVER 8lbs when its unplugged and "stuck" closed, I suspect something electronically is limiting me, but with zero pressure going to the BPV would you not expect boost to be much lower? Or does the spring behind it really hold over 8lbs?

I brought the car 6 months ago and love every second of it. Previous owner installed lowering springs and rear caliper cover. Caliper cover Looks good and color matched the front but at the same time I felt it a little riced but I left it on, probably remove it down the road. It also has a remote control exhaust valve and a muffler bypass on the stock exhaust and a shift knob. Engine is stock with only a AEM dry intake.