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Focus MK1 Misfire


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Hi All, 


Hoping for a bit of help before I give in and end up in a mechanics :sad:. I Have a Focus MK1 2L Zetec Petrol Blacktop, Until recently it has been performing fine with a service done recently. All of a sudden I felt a judder coming from the engine. I Ran a Diagnostic Scan and came back with a P0304 Code, Misfire Detected. The Scan also showed the following errors 

P0141 - o2 Sensor Heater Circuit Bank 1 Sensor 2

P1131 -  Lack of Ho2S11 Switch - Sens Indicates Lean

P0171 - System Too Lean Bank 1

P0136 - o2 Sensor Circuit Bank 1 Sensor 2


Now I'm by no means a mechanic but my understanding would be this is to do with the MAF Sensor and Lambda Sensor may have gone ? Would this the Cause of the misfire ? or not ? I have checked the spark plugs and HT Leads I have checked the Coil but not sure what Ohms Reading I should be getting back as ok. My Next Step would be to check the Injectors and pump again not sure what omhs readings I should be getting for that to be ok.

The only other thing recently I have done was given the engine bay a bit of a clean and wiped some oil residue away from the rocker bay area so could it be due to that ? I Have Read the PCV Valve and the IAT Could also be the cause.

I'm quite happy having a go at most things so any ideas or suggestions do feel free to mention.


While I Had the scanner attached I pulled the latest Live Data Set too which may help diagnose the issue 




LOAD_PCT(%) - 31.4

ETC (F) - 163

SHRTFT1 (%) - 0.0

LONGFT1 (%) - 0.0

RPM (/MIN) - 887

VSS - (MPH) - 0

SPARKADV ( ' ) - 22

IAT (F') - -40

MAF (LB/MIN) 0.077

TP (%) - 16.1

O2SLOC B1S12--B2S----

O2B1S1 (V) - 0.035

SHRTFTB1S1 (%) - 0.0

O2B1S2 (V) 0.000




Any and all suggestions greatly appreciated 

many thanks 


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