Renault Clio III 2007 1.6L 16V no O2 sensor signal

Generally, I use the brake booster vacuum line to test my AFS/O2 sensors since it is usually easy to get to and it is large. When you disconnect yours, make sure there isn't a check valve between you and the intake manifold.

I put propane right into the brake booster vacuum line that goes into the intake. Your AFS/O2 sensors should quickly go rich. Once they do, I remove propane and cover hose with thumb and let the engine go back to 'normal'. I then remove my thumb allowing atmospheric air into the intake via the brake booster hose. Your AFS/O2 sensors should go lean.

I think you said you have a simple scanner and DVOM. When I do this test on a scanner, I prefer a graph display to view the sensor's response time, be sure to reduce the number of PIDs displayed, allowing a better data refresh rate. But, the best way to determine response time is via an o-scope. But, I think you said you don't have that.

If you look at the attached picture, you'll see me directing propane right into the brake booster vacuum hose. Don't let the picture fool you since there is an EVAP hose right underneath my hands. ScannerDanner videos will go into way more detail.

Best of luck. Your persistence will pay off.

I'm kind of afraid using carb cleaner onto the brake booster vacuum hose will damage the electronic throttle body, should I be concerned? Can't think of any entry point after the throttle body tough... thanks for the picture and the encouragement!

Some updates on today's test drive:

- Unexpected: front o2 signal went really weak after less than a minute after a cold start.
- sensors seem responsive even with the signal problem present: if I open the throttle, voltage increases, although not by much (in the plus minus 35mv range).
- only managed to get a different code this time: P0140 (related to front sensor circuit instead).

Something I find interesting is that HEAT seems to be playing a role here: when I turned the engine off with the problem present and the signal weak on both sensors, it took a while for the sensor signal bias to go to its 450mv value. Took about 3-4 minutes of cooling to reach that point. This is why I'm thinking this has to do with some wiring issue, even though I couldn't find anything during a visual inspection.

And now I'm not so sure it's only related to the rear O2 heater circuit.

I already started looking for a wiring harness replacement as it doesn't seems I'm able to narrow down the location of the problem

Thoughts? Thank you very much guys...

PS: I'll try to upload some scan data screens tomorrow.

hi again firstly you have nothing to worry about regarding adding carb clean to richen the mixture and prove or disprove that your 0/2 sensor is functional when pegged at 0 ,you will not hurt or damage anything as I mentioned before its only air mass meters that we avoid contact with

If when added the front 0/2 goes full rich you should at this moment move away from the worry that you have a wiring issue !

You mention that your looking to replace the loom already ,for me thats way way to soon you really need to have faith in the diagnostic procedure .

Let's just say the wiring loom is causing your problem ( for me at the moment I doubt but possible of course ) if its causing your problem ,which is the signal return to the pcm being at or near to 0 volts hence the possative fuel trim . This can only be a short to ground on the signal return or low voltage to the sensor ,but you've checked it has 12 v and from memory you said you had done a buy pass test with your finger (12v on bat + and other hand on signal return ) and it was good so why would you change the loom at this point ?

For me your front 0/2 sensor is your primary input for fuel trim ,at the moment it's telling the computer you have a lean condition ? If you add the fuel and it reacts you do have a lean condition (step 1)

Your map sensor is your primary input for fuelling ., if your running lean this is where I would start in this case .if this input is incorrect ,which if your pid of 7 psi at idle is really what the pcm is seeing then indeed it is way off then here is your main problem .yes you may have more than one issue but you can't accurately diagnose and output with a faulty input

Danner has loads of videos of adding a fuel source for 0/2 response and checking a map sensor ,worth the very quick test before your bin the loom

I have to admit that I'm getting desperate here!

On the MAP sensor: I didn't expect that. What is then a normal range of reading at idle? I was suspicious of it before the O2 sensor issues, but never was able to confirm it was bad. Will also look for videos from Danner on how to test that.

On the loom: I regret having tear apart most of the wiring searching for some sort of damage there. I wasn't able to confirm visually, but in truth, I don't trust my skills on this yet.

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I'll share some data I got on the last test drive on March 12th (PART 1 of 2):

www.dropbox.com/s/o9j7lvikjiu8e91/Screen...12-21-43-34.png?dl=0 -- Cold start, front O2 seems normal, rear O2 on its bias value

www.dropbox.com/s/fsn2wf8yvxo2r4q/Screen...12-21-43-54.png?dl=0 -- Unexpected. Only 20 seconds after, front O2 signal gets week. Correct me if I'm wrong, but for what I've seen on Danner's videos, this looks like a signal short ground somewhere. And in this case, heat doesn't seems to play a role here.... could it?

www.dropbox.com/s/hte0upr634u1r9s/Screen...12-21-55-27.png?dl=0 -- Restarted the engine, front O2 signal got back, and 12 minutes after the cold start, rear O2 voltage starts to slowly rise. This, I suspect, is due to exhaust gas heat. (When I grounded the rear O2, signal went up faster).

(Continued on part 2 of 2...)

(Part 2 of 2)

www.dropbox.com/s/adei88kv6t87k8d/Screen...12-22-21-21.png?dl=0 -- Engine turned off. I expected bias voltage at its 450mv values, but instead, I get a slow climb from about 300mv on front O2. Heat resistance? I also noticed some "interference" on rear O2 signal. That made me think somehow the signal was getting shorted to ground?

www.dropbox.com/s/tnezhhz6dxozxxl/Screen...12-22-23-19.png?dl=0 -- Two minutes after, I start the engine again to see if I could get the O2s to respond to throttle. And they do... right? Notice STFT is at 99. This is what the car does when the signal goes weak.

www.dropbox.com/s/o55bze7eipssq08/Screen...12-22-29-22.png?dl=0 -- This is the kind of "interference" I hadn't noticed before. On both the front and rear O2s (different times) www.dropbox.com/s/sanc7z2tim8tfnn/Screen...12-22-29-00.png?dl=0

All of this is what makes me think of wiring issues... what do you think?

(I've been trying to get help with a reading from a Renault Clip for the multiplex network, where, allegedly, you can diagnose some wiring issues as well. No luck yet.)

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Anyway, will do my best to go back to basics and test for responses with carb clean and report back.

Thank you very much guys. Please don't hesitate to share any thoughts on this.

Chris,

I was just looking at this video from Paul and made me concerned about using carb cleaner on a "drive by wire" throttle body.

Isn't it equivalent to spray carb cleaner on the brake booster hose, given that the liquid will have to pass unburied through the throttle body?

Sorry if I'm being too insistent here, it's just that I don't want to make more damage to the car...

Thanks!

Hey Chris,

Forget about my previous post, I realized the brake hose goes after the throttle body. So I did a (valid?) response test with carb clean.

This is just after the issue presents itself: www.dropbox.com/s/2j7yr4j29umlcj5/Screen...15-00-18-49.png?dl=0 (notice how the rear O2 decreases voltage).

And this is what I got while adding (a little?) carb clean with the issue present: www.dropbox.com/s/vpe3ux8fd9oegl1/Screen...15-00-19-57.png?dl=0

What do you get about the O2 sensors health with that? Front O2 oscillates normally (between 100mv and 800mv) just seconds after cold start. Rear O2 stays at 450mv for about 10 minutes before it starts slooooowly climbing. And this time it didn't reach more than 700mv: www.dropbox.com/s/oh9cc7odwgc0ry1/Screen...15-00-15-30.png?dl=0

Think I mentioned before, both O2s are new, and supposedly, original OEM. I did some measurements on all 4 (2 old ones, 2 new ones) and resistance at the heater match.

What's next?

Thank you all again.

PS: I tried fiddling with the wiring harness to see if I could provoke the issue with both switch on only and engine running, no luck though. Couldn't reach many spots under the battery and so. Spacing is really tight.

Hi...i am a new user here. In my case I had bad earths on the car and found that if you put the blower motor on and heated rear window it would flat line the o/2 sensor ? I cleaned all earths up inc the pcm ones behind the bat and this solved the problem .I use a snap on solus to command the heaters on the o/2 on but the tool commanded the oppersite 0/2 heater to the one selected which trough me through a loop for a bit ,just a software issue with the tool but worth remembering if you use a tool to command the heaters on .

Thanks, will try to replicate turning on blowers, heaters, etc.

I did clean earths behind the PCM and the engine. Have a couple left in front of the battery.

Wish I have a tool to command actuators on the vehicle!

Hi again ,well first before I forget i made a mistake ! I remembered that some scan tools include atmospheric presure in readings ! So we all live at 1 bar 14ish psi so on your tool we need to take that away ,it was a passing comment from an instructor on a training day at it just hit me sorry sorry about that my tool shows map in kpa or I use a gauge and you want to see 20 ingh on a good engine ,so guessing that's 7 psi on yours is about 14inhg of vacuume so a bit low .. do you have a vacuume gauge ?

So a couple of things just to be sure when you next take a capture/ screen shot can you include the loop status . ,so my thought is for sure that when the trim gets really high it drops out of closed loop (which is when the ecm is using the o/2 signals for fuel trim )

When you added fuel to the booster hose as soon as you pull it off you create a vacuume leak so do remember to squirt in the fuel and close the pipe with your thumb or reconnect imidiatly ,any chance you could repeat the fuel test give it good 2 seconds worth of a squirt and if you can do it at the manifold so it doesn't have to travel all the way down the pipe ,just want to be sure the test you have done is valid and we can move on just a bit unsure as you had reservations on using fuel that you gave it enough !

Interesting that another post Had same problem as I mentioned that I had about bad earths did you say you checked them all after I mention that?

I forgot to ask before this original heater code , the reason you swoped out the o/2 s was the car running fine ?was there any other codes ect

Before you do the retest clear all the fault codes and clear the fuel related data this will return the long term to 0 just in case the ltft hasn't altered as I. Guessing it's not been driven since the o/2 swop this may just keep it in closed loop for longer while we test

Then if your fuel adding does nothing (reaction )we look at the wiring and as somone else had the same problem as me for sure a re check of the Ecu ground ,in the mean time if I get the chance I'll look for a wiring diagram for your year I know it's different from mine but I may have it

Just a quick answer regarding wiring diagrams: I have all of them for my make/model. I can send them if it helps.

Also, I couldn't find any PID on loop status in my scan tool. Will check thoroughly tonight.

On the carb clean test: I'm sure I did it wrong, for starters, I didn't put my thumb after the sprays. Got scared because on the first 2 sec squirt, the engine stalled. Not sure I can find an entrance directly to the manifold, at least not with easy access.

Before I changed the O2s the issue was no signal on the front one, I remember a code on the front o2 signal circuit. Not sure if related, but this happened after a cooling fan wiring repair (done by a mechanic, not me. Wire insulation going to a relay peeled off, fuse blown, relay blown.)

So just checked I do have a diag for your car and the earths are the same as mine so special attention to ep3 which is on the lh bulk head and ep1 which is behind the kick panel bottom of a pillar (do both a pillars earths not sure if your rhd or lhd or if it changed )also although they don't seem relevant there are ones behind each headlight and rear lights ,I cleaned all mine up even though they looked good ,I've turned the laptop off now as its late but I thought the lh rear light earth is also used for something to do with Ecu comunication from memory although I maybe wrong on that

Thanks Chris. The ones behind the lights sound suspicious because I have an issue with lights flicker.

Will check their location once I get home.

Thanks and good night!

Hi sorry our messages crossed , that's great info it could be related
Re test with fuel if it stalled just as you put the fuel in that would say you put in enough / a bit much but would prove we have an issue with the sensors but have another go where you did before just put finger over and if it stalls again it's just because it got the fuel in a big lump .

When the issue is present does the exhaust seem rich ? Black smoke and smell of petrol ?

When you next look at the car remove the fuse and relay for your fan and see if you get a change and also just simple things to try use a jump lead from the battery earth and clamp it to the Ecu Earth for a few mins and see if you signal on the 0/2 improves you can You can do this to each of the earths and the engine block as well just a quick and simple way to see a difference don't forget to touch the actual wire/ loop not stud that it's bolted to good luck

Can't you please clarify what is ep1 and ep3?

I have a list of earths and connections and none of them are coded as ep1/3.

www.dropbox.com/s/8551efulm7frrbg/REPMAS.PDF?dl=0

Connections: www.dropbox.com/s/zmgi8sqijuw3ivg/REPLIA.PDF?dl=0

ECU wiring: www.dropbox.com/s/tmsz5xw998v1duh/K4M801-X85BVA4.PDF?dl=0

Components numbers: www.dropbox.com/s/vre2bg3lxh07cs7/REPORG.PDF?dl=0

Renault Megane TCe 115 - The engine had two cylinders missing compression and was replaced.
After a while I had a P0135 - O2 Sensor heater malfuntion with the new engine.
The front O2 signal oscillated at start, but after a few minutes it was flat and around 0,5V.
O2 sensor was replaced and works OK.
I guess it was contaminated with oil from the old engine, so maybe do a compression test....

Hi sorry ep1 stands for earth point 1 so basically you have 2 points behind the left headlight !infront of battery they sit on top of the chassis . You have one next to the Ecu and the main battery neg further to the right of the Ecu . You then have on the a pillars and from memory I removed the glove box to find the one on the passengers side .you also have the main earth cable to the block which you can miss it bolts I think where the gearbox meets the block at the front of the engine .so ep1 was on the a pillar passenger side ep3 was next to the Ecu oh and mine does have a good earth connection to its housing meaning if you check the housing / body of the Ecu it's connected to earth via its bolts weather internally it's connected I'm not sure but just check it is earthed .i removed all mine regardless cleaned them and put them back

Remember if you check earths it should be a loaded curcuit so really whatever it goes to / being used for should be on ,in your case if you clean them all up then run the car with everything on and then check the earth with one lead and the other on neg . battery Danner has a load of videos on this

Thanks Chris!

I've been studying wiring diagrams focusing on earth locations and how do they interconnect with each other. It kind of makes more sense now on how they could be related (I wondered how an earth not directly connected to the ECU could affect signals, but as they all interconnect to the Protection Switching Unit, that would kind of make sense).

I saw the ones you mentioned in front of the battery and.. this looks suspicious, right?



I'll take my time to clean most earths I can access, and check on proper cleaning/repairing procedures.

I'm hoping this is it!

PS: ECU has a bolt missing on the body, will look for a replacement nut as well.

I was in the same place trying to work out why the heated rear screen and blower motor effected my 0/2 .as far as I understand if a item say motor has a bad ground it will load the ground with voltage ,as all grounds are connected it will / can effect anything connected ,have a look at danner video on bad block ground I think the engine was charged with 9 volts worth a watch .

The wires you show defiantly look bad ,is there melting on some ?

when you clean them just unbolt use some sandpaper or Emory cloth and make them bright and bolt back up ,don't forget what I mentioned about using the jump lead as a temporary ground from battery neg post to the engine block see if it prevents the problem and then repeat with it attached to the Ecu ground to bat neg