My 2003 focus lx 2.0L L4 SOHC ~18,000 miles has had the engine light so i went to autozone to read the code. Autozone obd2 printout says "P2195 lack of heated oxygen sensor- Bank 1 Sensor 1 HO2S11 switch- sensor indicates lean."

Autozone said "Your car is burning more fuel. It's a common problem. It's usually the 1st sensor to go out. It's possibe to DIY. It looks like a spark plug in the exhaust pipe before the catalytic converter by exhaust manifold."

I checked with Herko Automotive Group and they said "For your car 2003 FORD FOCUS 2.0L L4 SOHC in the position sensor 1 (Upstream) you need the oxygen sensor number SG1813."

How reliable is this advice from autozone & herko? Should i just replace the sensor or what's the next likeliest fix for this?

I think I see where the bank 1 sensor 1 is located in front of the engine, but can someone post a pic highlighting the location?

2 Answers 2


since installing new 02 sensor engine light has not reappeared after clearing w/obd2 device and torque free app. TOTAL COST= ~$27

7 31 13 ordered Koolertron F-12 ELM 327 OBDII PC Car Diagnostic Scanner Electronics EggDeal via amazon $9.50 to use w/android smartphone torque free app to read & clear obd codes

8 10 12 friend sprayed hoses he knew to be for emissions in engine w/water from spray bottle while car running and it didn't choke or stall. ws able to get o2 sensor loosened w/ 22 mm wrench. (if can't get off 02 sensor without removing heat shield then nuts on heat sheild need 10mm wrench). friend didn't think we had any vacuum leaks but thinks should replace vacuum gas pod as he heard funny noise in it but we're going to replace 02 sensor first since that's what autozone recommended & since there aren't any vacuum leaks.

8 11 13 bought new o2 sensor to replace bank1 sensor1 NEW PREMIUM HIGH PERFORMANCE O2 OXYGEN SENSOR FORD LINCOLN MERCURY GA24302 ebay 380658246257 $16

8 15 13 rcd o2 sensor & rcd obd2 bluetooth scanner

8 18 13 used obd2 scanner w/torque app to clear engine code

8 19 13 ws abl to twist off o2 sensor by hand (as it was already loosened w/ 22" wrench when was at friends 8/10). picked up anti seize lubricant at autozone $1.39 which i applied to threads of sensor (*careful not to get on head of sensor) b4 screwing on by hand then tightning slightly w/wrench

9 6 13 it's been almost 3 weeks and engine light has not reappeared


The diagnostic trouble code is not to be looked at as a root cause of the system failure. (example. Replacing a blown fuse is NOT a solution) In all cases there are multiple components that can cause the same code to trigger. For instance, a possible vacuum leak, or EGR problems, and even a PCV issue, could all show o2 sensor readings with tendencies towards lean.

With that being said checks should be done to ensure that problem isn't elsewhere and that you're replacing the correct part the first time and now just blindly throwing parts at a car. But, if you feel like rolling the dice and hoping that it is actually the oxygen sensor then feel free to replace it.

Bank 1 Sensor 1 is located before the Catalytic Converter. The one after the Converter is Bank 1 Sensor 2

  • tx. what "checks should be done to ensure the problem isn't elsewhere?" if you could answer in simplest terms it would be much appreciated.
    – catjacent
    Jul 26, 2013 at 19:50
  • 1
    Check for any vacuum leaks (broken vacuum hoses) the best way to do this would be to use a smoke machine, Check to make sure the EGR is not clogged and if functioning properly. For this test you can pull the vacuum line off that leads to the EGR Valve and with a vacuum pump apply vacuum to the valve while the vehicle is idling. If functioning properly it should cause the idle to change. If there is no change then the valve is either broken or the EGR is clogged and removing the EGR will be needed for further inspection.
    – cinelli
    Jul 26, 2013 at 22:37
  • 1
    You will be able to find a diagram for anything at tousleyfordparts.com . Here is the photo of the egr valve tousleyfordparts.com/media/images/oe/collision/J/JK00220.gif
    – cinelli
    Jul 31, 2013 at 3:33
  • 1
    thank you. i searched this site last week for pix. after entering my car info and clicking on "emission system" and even adding it to the cart, i could not see any pix. how do you bring up the pix for each system/part? tx for that photo of the egr valve system. i think the o2 sensor is #5 in that pix but it does not indicate the names of parts numbered in that pix. i need to see pictures or preferably video where the parts are clearly illustrated and correlate to what i see when i'm looking at my car.
    – catjacent
    Jul 31, 2013 at 15:37
  • 1
    tousleyfordparts.com/parts/2003/FORD/FOCUS/LX/… select a part and there should be a diagram for most. match numbers in pictures to components in the list on the right.
    – cinelli
    Aug 1, 2013 at 3:22

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .