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Fiesta MK8 ST-line : O2 sensor DTC after Stage1 upgrade


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I'm a little unsure IF this is really related to the remapping I've done recently with a Pumaspeed Stage1 to my Fiesta MK8. The car is from feb 2019, and have not had any major issues with it whatsoever. Warranty is now out so i decided to remap it with a Stage1 DIY kit from Pumaspeed along with their Cyclone Cold Air Induction System. Everything went smoothly and the car is performing well, but only a few days after i remapped it and installed the Air induction kit my yellow engine light came on. 

So i read the cars DTC codes and got the following:

Quote

Code: P0141 - O2 Sensor Heater Circuit (Bank 1 Sensor 2)

Status: 
 - DTC Maturing - Intermittent at Time of Request
 - Malfunction Indicator Lamp is On for this DTC
 - Test not complete

Module: Powertrain Control Module

I tried clearing the code and it came on again a few rides later.. Tried swapping to the original air intake, reset the code, but it once again came back on. Now I've reset the DTC one last time after i remapped the car back to its stock / factory map, but haven't had the time to take a ride in it yet and see if it changes anything.

But my question is, if its just a coincidence that the sensor is dead or w/e where is it placed? When i first saw it, i thought it had to be the sensor placed on the end of the hose of the induction system just before the filter it self, since this was the only thing i had been tampering with. But searching online this sensor seems to be placed on the cat which I've not touched at all, and if that is the case its either a coincidence or the remapping which has damaged it somehow. 

Any tips?

Wheres this sensor located?

Can anyone recommend a service manual to troubleshoot things like this for the Fiesta MK8 ?

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O2 sensors tend to be on the exhaust to measure the oxygen content in the exhaust to make sure the car has the correct AFR, it could either be a faulty sensor or the sensor may have got unplugged

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2 minutes ago, Neb_engineer said:

O2 sensors tend to be on the exhaust to measure the oxygen content in the exhaust to make sure the car has the correct AFR, it could either be a faulty sensor or the sensor may have got unplugged

Might be. I've just not touched anything below the car. I only changed the induction. It just seems a bit too much of a coincidence if the sensor just died right after i have changed the filter and remapped the car. You would think it would have something to do with either of those two things, but changing the filter i shouldn't be able to unplug anyhing on the exhaust 

Besides the engine light doesn't come on right away when i reset it .. It usually takes a few rides. If i had unplugged it shouldn't it come on straight away?

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this DTC is for the sensor's heater circuit, O2 sensors have integrated heating element to heat up the sensor quickly when you do a cold start so the system can enter closed loop quickly to begin monitoring air fuel ratio and adjust accordingly, a DTC that relates to the heater circuit could possibly mean only two issues, either the connection to the sensor is compromised somehow so the heater works intermittently, or the heater element inside the sensor has failed which requires a sensor replacement.

so I would start by checking the connection to the sensor if it is plugged in correctly, I would check the wiring to the sensor also for any damage , may be the wiring touched the hot exhaust pipe or the heat shield for the catalytic converter and got burned out.

if everything is OK then I guess that the sensor failed, but before attempting to replace the sensor I suggest a visit to a good specialized garage to recheck 🙂 

keep us updated 🙂 

edit : bank 1 sensor 2 is the downstream sensor , after the catalytic converter, not the one before it 🙂 

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15 hours ago, Da9L said:

The car is from feb 2019,

 

15 hours ago, Da9L said:

Warranty is now out

 

The warranty is for 3 years so a 2019 car will still have at least 1 years remaining

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1 hour ago, robbyvrs said:

 

 

The warranty is for 3 years so a 2019 car will still have at least 1 years remaining

It won't have a warranty now he's modified it. 

But yes, it should be for 3 years, it is in the UK, not sure about other locations.

 

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2 hours ago, Blatto said:

It won't have a warranty now he's modified it. 

But yes, it should be for 3 years, it is in the UK, not sure about other locations.

 

Only listed as two years here in Denmark unfortunately. 

Anyway i tried driving it today with all being stock, and the engine light still came on after 10 miles or so. So guess i will have to look into it. 

Not sure where its placed though. Is it visible from under the hood or should i below the car? 

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The connector that is for the catalyst monitor sensor is under the air intake pipe. 2 connectors side by side near the engine . It's the left connector of the 2  as you look at it from front of car. Check you haven't disturbed it. I doubt it as you would also have another dtc for the sensor part of circuit. Check the wiring down to the sensor for damage . The sensor is located/viewed from under the car. 

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2 hours ago, iantt said:

The connector that is for the catalyst monitor sensor is under the air intake pipe. 2 connectors side by side near the engine . It's the left connector of the 2  as you look at it from front of car. Check you haven't disturbed it. I doubt it as you would also have another dtc for the sensor part of circuit. Check the wiring down to the sensor for damage . The sensor is located/viewed from under the car. 

Just checked under the hood. Removed the hose which has one end attached to the filter box and looked below it. Are these the plugs you referred to?

9508BE29-6F18-4B0F-A330-310BA61CAB30.jpeg

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Yep, buried a bit so no way you've dislodged the connector. Sounds like a coincidence or map related. Have you driven it since putting the original map back on? 

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Just now, iantt said:

Yep, buried a bit so no way you've dislodged the connector. Sounds like a coincidence or map related. Have you driven it since putting the original map back on? 

Yep i reset the DTC's after i had put the original map back on, and after a 10 mile drive it came back on again unfortunately. But could the stage1 map have been the reason for it to be damaged? Just wondering if i replace the sensor, and remap it again, if it would damage another sensor 

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the heater is within the sensor so if the map had damaged the sensor it would be more than the o2 sensor heater fault code, it sounds more like a coincident than the map causing it

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9 minutes ago, Neb_engineer said:

the heater is within the sensor so if the map had damaged the sensor it would be more than the o2 sensor heater fault code, it sounds more like a coincident than the map causing it

I think you are right. I also think its easy enough for me to replace my self. Just need to get a spare.

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