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

There was melting on the cooling fan connector, but it was replaced (not by me, I hate the way the technician crimped the new connector's wires, will see if I can do a proper job there).

I still have to check that wire all the way up to the relay box, see if there is more damage. I recall seeing one wire from the relay box to somewhere else damaged as well.

Should I do the engine block jump test before fixing the wiring? I did check with one lead on B+ and the other directly to the engine block and I didn't get any voltage difference.

I didn't take a picture, but the ground behind the headlight (in front of the battery) looks kind of dirty. Im thinking maybe, when the cooling fan runs, since it might not be properly grounded due to the damaged wire, it put voltage on the ground line and messed up with the signals at the ECU. Could that be possible?

I have to get some electrical supplies to perform the repair. It will be my first one.

Yes I think it could be possible . I'd check and clean your earths first and go from there good luck

Quick update:

Cleaned up almost all earths at the engine compartment (couldn't reach one behind the right headlight, car is left hand drive). I expected the light flickering to go away but it didn't.

The flickering is for some kind of led bulbs it got installed just after I bought the car used. No other bulbs flicker though.

Also, checked the damaged wire up to the relay box and its damaged at the relay box as well. Actually, relay connectors are melted from before the repair. And if i touch the box after a few minutes with the engine running, it feels quite hot. Not sure if this is from engine heat or from excessive resistance.

Issue took longer to set in after the earths cleanup. I tried putting a jumper wire from ECU earth to batery ground, removing cooling fan fuse+relay, even removing some fuses at the protection switching unit and no improvement once the issue was present.

I still think the issue is caused by some kind of excessive heat in the wiring, but could certainly be wrong.


Not sure what to do now. I'm close to give up... really wish I could take it to Paul or something.

Well don't panic yet all we've done is confirm the o/2 will not respond to fuel so somethings pulling it down so we then check the loom ,we check the 0/2 and move forward

So there are several thingsI would do ,when fault is present

1) umplug o/2 and do a risitance check on the sensor between your signal return (blackwire) and the following a) the body of the sensor b) the heater ground wire c) the signal earth (grey) make a note and do both sensors

2)if you haven't already ,check all your earths with your meter to confirm there ok

3) I would swop the front and rear 0/2 sensors over I'm guessing they are both the same on yours and see if the problem changes ? If it does this would be a dodgy sensor

4)then I would check the earth on the front and rear 0/2 when it's pegged at 0 (fault present ) see what its value is it should be close to 0v so that's bat neg to your o/2 signal negative (grey wire)if it is then good we move to checking for a short on the signal wire .. So to do that I would again wait until it's pegged to 0 v so car hot in your case ,I would back probe the signal return (black) and while watching the scan tool add voltage (by the finger on bat +) if it goes up imidiatly its not shorted but if it doesn't then it is shorted and then in that case We can hunt for the short

Let me know the results of these

In theory O2 sensor doesn't need a car connected to produce signal output. If you totally unplug it and check the signal output? Or even connect its heater circuit to a battery source. If it is low add some carb cleaner to intake if high - vacuum leak.

Quick update: went to a neighbor's friend shop to gather some better scan tool data and got to see these codes present or stored (couldn't see well their status, he was too quick at deleting them).

Injection:
DF084: Actuator relay control circuit
DF436: Detection of engine misfire (Stored)

Not sure if I saw well these on the ENGINE COMPARTMENT CONNECTION UNIT:
DF001: +12V APC Relay Control Unit

It also showed that the Flywheel programming hasn't been DONE. However, the tool didn't offered the option to trigger the programming.

Heaters get ACTIVE before the issue shows up. For both O2s.

Unfortunately, they applied the classic "Let's delete the codes to see if they come up again; then we'll chase them". So I couldn't see more data from the scan tool.

Another guy at the shop told me that he had one of these cars for repair, and he even shown me the UPC he was trying to repair. It's the same part as mine's.

Once they deleted the codes, car was running fine for about 20 minutes, but the fuel issue seems to have reappeared.

It sure makes a difference having that data.
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On the texts mentioned on your last post Chris:

1. Earths seem fine with engine running, at max 0.03V from B- to each of them.
2. I had swapped sensors before. No difference.
3. I performed a continuity and resistance test on the sensors when had the Heater circuit codes. Resistance is about 16ohm on the heater, have yet to check from signal circuit to the sensor's body though.
4. Unplugged and cleaned the right headlight connector, checked earth there as well. Had an issue with the headlight getting water inside and corroding the entire bulb holder useless. (I'm waiting to fix this issue to tackle this one as well, hoping it's just about a replacement!).

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So, maybe there's some damage on the Engine UPC unit's relays and it gets deactivated when some voltage issue its generated by the cooling fan circuit? I'm currently digging for more info on how to troubleshoot those faults to see if I can find clear evidence on something!

It's though to perform measurements with the engine running because there's no space left to be checking connectors/wirings.

And it'll be a challenge to find a spare for that here without loosing an eye at the dealership here! (Be it a new/used loom or UPC).

Let's see how long can I persist on this. Your support really helps guys.

Thanks!

Hey guys,

Just wanted to report back on this. After 3 days of having had help erasing those manufacturer codes, the issue seems to be gone.

Car runs almost fine now, no overheating (coolant temp), O2 signals remain active, and was able to see heaters being activated by the PCM (with the PIDs at the scanner.)

Another anomaly detected was the TPS min-max values. Flooring the pedal only reached 60%. After reprogramming, it shows 89%, and the cars feels a lot more responsive, although with the occasional setback (that feels like a possible exhaust issue).

Also found that the "Flywheel target programming" wasn't done at the time of the last scan. I performed the sequence that the manual says, still have to verify if it's DONE.

Only issue remaining is a slight vibration of the engine at idle (RPMs have a slight rhythmic oscillation. A mechanic suggested this could be either an engine mount going bad already, miscalibrated spark plugs (I know it's not using the recommended ones by the manufacturer), weak/incorrect ignition coils OR a slightly plugged catalytic converter.

In the end, I feel like a fool undoing the wiring harness when apparently the issue was a stored code in the cars memory. At least I find comfort in thinking the car is not as delicate as sometimes feels like.

Guys, I want to thank you for all your help and patience (Hey ChrisG!). And if you ever need some tech info on Renaults (wiring, manuals, tech notes), I think I can help with most models to date. Just DM me.

Best!

Hey great great news !! I hadn't got an email this time so missed your last post ,glad you got it sorted ,love to know how a fault code stored could do this ? I had woundered before weather the fuel trims where so far off with the last 0/2s that when you replaced them it didn't stay in closed loop long enough to reset the LTFT ?just trying to make sence of it ... But I'll take fixed any day and learn tomorrow! Well done for sticking with it ...and a good excuse to treat yourself to a new scan tool ,all the best Chris

Yeah, I would also love to get a more detailed explanation. My theory is that somehow the PCM enters in some kind of protected mode due to the presence of the DF436 code (Destructive Misfire), thus disabling the "double loop mode" and the rear o2 heater is disabled.

BUT:

Now I'm struggling with a fuel trim related issue: apparently if I leave the car idling, the LTFT goes slowly negative until it reaches about -60% and this in turn makes the car sluggish if I use throttle above "average".

Once it gets this low, the car starts misfiring (P0300).

There is a PID indicating that the fuel trim associated with the rear o2 is -100%, I was thinking the voltage of 700mv of the downstream sensor is being taken as RICH, thus the PCM trying to remove fuel?

This was the issue I had before the whole distribution mess started.

I already fitted new "calibrated to spec" spark plugs, o2s are new.

I'm hoping this to be more of a basic issue...? Should I open a new thread for this...?

Freeze frame for the P0300:

Oh no you have the same problem ! Nothing has changed

I thing my rear 0/2 pid also says -100% I think this is normal as ours runs good

There is no doubt that the car is pulling fuel away which creates your misfire code ,clearly in your last shot both o/2s are not agreeing !
I can't tell from your screen shot how long a time it covers but to be pulling away that amount of fuel when your front is showing lean is crazy how long a time does your pic/ screen shot cover ?

Is there any way your wiring harness could be plugged in the wrong way round ? Front in rear and rear in front ?conector

Don't think it's about the harness connected backwards, the rear o2 connector is waaaay longer to reach the sensor.

I'd say the time span of the screenshot is about 30s.

Yeah, feel the same way: all the heater issue seems to be a useless (well, lets say learning) detour.

Only thing I know is that sensors not agreeing with each other could cause an issue on Renault's thanks to the "double loop" feature.

Will try to do a better data capture tonight to see if other ideas come up!

Yeah sorry it wouldn't have given what you have

Can you delete the fuel data with your scan tool so your ltft goes to 0 sorry may have asked before ?

Well let's just say the double loop thing is causing your problem because the rear 0/2 is staying Rich ,if you short the rear signal wire to ground (while all plugged in using a jumper lead or test light with car running )pulling on your scan tool rear sensor to 0v ,you should see the fuel trims reduce in negative numbers as its seeing lean now and then go into positive fuel trims

Will try both ideas asap. I might have to lend the better scan tool from the tech I met recently to see if there are any manufacturer codes in memory. Shorting the rear o2 I can do to see the behavior of the fuel trims.

Any resources on what's a normal reading of a rear o2 with a good catalytic activity?

I've been told by another technician that he thinks I have a plugged cat judging from the amount of air getting out from the tail exhaust. Could be...?

If your cat was plugged I would exspect from a map sensed engine ,negative fuel trim numbers which you do have ,as the volume of air it calculates for is incorrect becouse if there's less getting out there is less getting in ,but the fueling stays the same ,hence rich condition but I would have exspected your rear sensor to have been lean ? Maybe I'm wrong on the rear sensor if the rest of the exhaust is blocked ?You could do a back presure test by removing the sensor and putting a presure gauge in the hole it should be less than 1 psi really .


Re your question On your rear 0/2 signal I would exspect around 650mv but we have to be mindful that yours is only slightly higher at 700mv BUT the car had -60 %on the fuel trims

Also with a plugged cat your intake vacuume would be low ,if you can borrow the scan tool check from the tec ,as if you remember we questioned the reading from the intake pressure before saying it was to high/ not enough vacuume but then discarded as we think your tool is including atmospheric pressure in its reading ,worth putting a vacuume gauge on the engine for sure if you have one 20 ingh is what we want to see on good engine

Had written an update but something went wrong while posting.

Here it is again: from the last test drive.





My thinking was almost like yours, except for the part where you expected lean at the rear o2.

With a plugged/degraded cat, it doesn't convert well, rear o2 reads high voltage (thinking its rich), PCM reads that and tries to reduce fuel gradually until the point where it's outside spec, creates the misfire due to lean mixture?

Also I noticed that the throttle body is back to a max of 60%, it was corrected with the better scan tool to have a max of 89%. Maybe it's some kind of failure mode?

Will go with the tech to get better scan data and do my best to confirm cat/exhaust issues. I might have to go to an exhaust shop to see if there is back pressure.

That MAP seems suspicious too, but I did some graphing and it seems to correlate with throttle position. Tech used carb cleaner around intake manifold and didn't seem to find a vaacum leak.

Oh well...

Images attached

Update: just saw this on expected rear o2 voltage at idling is 480mv.



I guess that means rear o2 is reporting rich?

And MAP reading at idle is expected between 240mb - 410mb.



Freeze frame at idle reported .44bar (440mb). Slightly above the upper limit. Exhaust restriction? Low compression?

I guess I have to figure out how to do a back pressure test. Either I find a gauge or find an alternative method.

Will report back as soon as I get more data.

Quick update:

Went to techs shop to see codes in memory. DF436 was there, deleted them. Told him about my theory of plugged cat. He suggested I take the car to an exhaust shop. Took it there.

The guy there checked and said he didn't see anything that suggested plugged cat from underneath. I asked if there was any way I could check from the inside, so he offered to take the cat down to see. Once down, we saw there are two honeycombs. The one on the front side was darker than the one behind. He then suggested he could take only the first one to see if that improved the situation.

On a desperate call (again), I took his suggestion. One hour later, no change at all. Even got codes for both o2s circuits. Deleted them and haven't reappeared yet, but vacuum and rear o2 sensors didn't improve. I'd even say rear o2 reading got slightly worse.

Fuel trims are still stuck negative.

Got back to scan tool tech and told him about that. He then suggested we do some test on Monday (compression test, adding pressure to coolant circuit) to rule out things like blown head gasket or possibly a engine valve damage or even slight timing offset.

Thoughts? Hate myself right now for the bad call on the cat.

Here's a pic of what the guy took off from the cat.