I had an issue with my Ford Focus mk3.5 1.5 tdci where the timing belt tensioner broke and skipped a few teeth (car started running very rough but it kept running).
The timing belt was replaced and I was assured the engine is fine.

Now I am getting the following issues:

1.  P1102  -  Mass Air Flow Sensor In Range But Lower Than Expected
2. P2279 - Intake Air System Leak Bank 1
3. P2463 & P246C - Particulate Filter Restriction - Soot Accumulation Bank 1 / Forced Limited Power Bank 1
4. Loss of power (Limp mode)
5. Smoke (black + white)
 

I am getting CEL and after a few moments Engine Service Now where engine goes into limp mode. While there is only a CEL, the engine has power but still feels underpowered.

So far I have:

1. Cleaned MAF / Changed MAF (not OEM). I am aware that I should go OEM here and will do soon but so far the current MAF shows ok values. 9 g/s on idle at 750 RPM.
2. Cleaned DPF + Forced regen - fixed the DPF issues but it came back after 1 week
3. Checked timing
4. Checked for leaks - can't find one and no access to a smoke machine

Next I'm being told by a local shop that gutting the DPF will solve the issue (I have no issues with this and MOT is not a concern for me) but I keep thinking it's the first issues causing the engine to run rich.
I have no skilled shops near me, Ford said I should replace MAF and DPF and then an insane amount to just have a look at the engine.
Anyone experienced anything similar as I'd like to hear your experiences.

On 3/31/2025 at 11:09 PM, EngineNoiseEndedMe said:

I had an issue with my Ford Focus mk3.5 1.5 tdci where the timing belt tensioner broke and skipped a few teeth (car started running very rough but it kept running).
The timing belt was replaced and I was assured the engine is fine.

Now I am getting the following issues:

1.  P1102  -  Mass Air Flow Sensor In Range But Lower Than Expected
2. P2279 - Intake Air System Leak Bank 1
3. P2463 & P246C - Particulate Filter Restriction - Soot Accumulation Bank 1 / Forced Limited Power Bank 1
4. Loss of power (Limp mode)
5. Smoke (black + white)
 

I am getting CEL and after a few moments Engine Service Now where engine goes into limp mode. While there is only a CEL, the engine has power but still feels underpowered.

So far I have:

1. Cleaned MAF / Changed MAF (not OEM). I am aware that I should go OEM here and will do soon but so far the current MAF shows ok values. 9 g/s on idle at 750 RPM.
2. Cleaned DPF + Forced regen - fixed the DPF issues but it came back after 1 week
3. Checked timing
4. Checked for leaks - can't find one and no access to a smoke machine

Next I'm being told by a local shop that gutting the DPF will solve the issue (I have no issues with this and MOT is not a concern for me) but I keep thinking it's the first issues causing the engine to run rich.
I have no skilled shops near me, Ford said I should replace MAF and DPF and then an insane amount to just have a look at the engine.
Anyone experienced anything similar as I'd like to hear your experiences.

Hi, did you get this fixed.
I have a similar thing.
Cambelt stripped and I got the first two errors you have:
1.  P1102  -  Mass Air Flow Sensor In Range But Lower Than Expected
2. P2279 - Intake Air System Leak Bank 1

My garage doesn't connect the errors with the cambelt but it seems you have something similar.
Any help would be gratefully received.

On 9/13/2025 at 9:18 PM, Harry_Worth said:

Hi, did you get this fixed.
I have a similar thing.
Cambelt stripped and I got the first two errors you have:
1.  P1102  -  Mass Air Flow Sensor In Range But Lower Than Expected
2. P2279 - Intake Air System Leak Bank 1

My garage doesn't connect the errors with the cambelt but it seems you have something similar.
Any help would be gratefully received.

It's been almost a year since I've been running the car after that event so I think in my case it's safe to say that the valves were not bent (or if they did it wasn't anything major). I forgot how the car used to run before but I think it comes down to a boost leak which no mechanic or myself could detect.

There are no emission control checks where I run this car so the only way I could get it to be usable again was to remove the DPF and map it out (it kept getting blocked). It runs better and no errors or CEL come out. It's pretty much dead in the RPM range 1000 - 1750 and it comes alive after that.

Only during summer I get an EGR Flow Insufficient code which again I attribute to a boost leak (and probably a poor ECU map) since the car smokes a crazy amount. I'm probably going for an EGR off soon.

Did you manage to get yours fixed?

If you have the tools:
1. Plug in Forscan and analyze boost and MAF flow in idle and during load
2. Perform a smoke test
3. Take a look at this issue (use subtitles): https://youtu.be/oBpjeqelbek?t=644

Best of luck!