Hi, I'm having problems with my Fiesta with a lack of power and the engine management light turning on and off!!

I took my car to a friend with a diagnostics kit and it showed the following codes:

HO2S-11 (Heated Exhaust Oxygen Sensor Right Upstream) Circuit Slow Response
System Too Lean Bank 1
HO2S-11 (Heated Exhaust Oxygen Sensor Right Upstream) Circuit Malfunction
Invalid fuel tank level message from instrument cluster
Knock sensor 1 circuit malfunction
HO2S-11 (Heated Exhaust Oxygen Sensor Right Upstream) Circuit Slow Response

I changed the Oxygen sensor back in 2014 - Could this have gone already?

I would be extremely grateful for any advice anyone may have for me!!

 

I would be looking at the mixture the engine gets. It seems to be lean.
OR you have a leak in the first part of the exhaust near the oxygen sensor.

What's your fuel consumption doing? Same, higher, lower?

 

OK thanks, may sound slightly stupid but I'm new to this - How would I test if there's a leak?

I would say it's about the same.

 

Start the engine, block the end of the exhaust and without a leak the engine should stall.
With a leak the engine keeps running and you should be able to hear where it leaks.

But with the fuel consumption being about the same, I would say the cause is something different. Maybe a leak somewhere around the inlet manifold or a defective sensor.

Can your friend read live data? Then check the "Fuel Trims".
They should be close to 0%.

 

what brand of sensor did you use? i wouldnt recommend anything other than a bosch one. if its a cheap'n may well have gone again,

other possible causes, expended or blocked CAT (do you notice any bad smells coming from the car?) , possible wiring malfunction

did he clear the codes and retest? or just a single test, i would clear and retest as it eliminates previous faults that could have been cured and still recorded.


my neighbours fiesta had a lack of power issue, turned out to be blocked CAT causing backpressure in the exhaust system and making it run bad , check all the basics, plugs fuel filter etc, does it misfire? blocked cat could explain the lambda sensor reading bad

 

Hi,

Problem was the Lambda sensor! Orignal sensor I used was HAAS - Must have been faulty!

I've now replaced with a NGK sensor and its worked a dream!!

Thank you both for your replies, much appreciated.