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Limp mode when full throttle at ~3/4k rpm. P0120 code



Cliomaxx69

ClioSport Club Member
  Clio 172 2002
Hi everybody,

I have a limp mode problem with my 172. I know it has been covered many times but I can't find anyone who had the same problem.

My car drives fine and limp mode only appears when I give it the beans, I drove it normally for an hour today and when full throttle a few times and after a few pulls it went into limp mode.

Stopped the car, checked the codes and it said P0120. Turned the car off and started it again and it was gone. It has come on 3 times now and only when I am at full throttle between 3 and 4 k rpm. Never when I drive in the city not going full throttle and above 3k rpm.

Any ideas? I thought the wiring but wiring would be intermittent and not every time I accelerate hatd wouldn't it? And if it was the spark plugs it wouldn't be P0120 right?

I should mention I had a bit of a problem, not going into details but got a few bent valves, got them replaced by a guy in my area who knows the F4R very well, could he have done something wrong in particular while in the process of fitting new exhaust valves?

Cheers.
 

hopgop1

ClioSport Club Member
I've been through this with my car, mine was intermittent and basically random, not related to throttle usage, so potentially not exactly the same problem, but the same fault code and limp mode. Mine is a 182, but assume it's the same setup on the 172 non-cup.
As I understand it, it could be the throttle pedal, the throttle body, the wiring for those items, or the ECU.
I had mine diagnosed by a specialist as the throttle body, replaced that with a brand new item, resolved for a long time, issue came back so I threw a verified low mileage throttle pedal at it, no difference. I then had a second hand ECU 'virginised' and replaced and issue has now gone for good. Looks like ECU is the rarest cause, so I'd do that last unless you've got reason to believe it's been shorted out or something.
 

Cliomaxx69

ClioSport Club Member
  Clio 172 2002
Yeah I have a few things to check before, only thing I could think of is that it stayed outside when it rained a bit with the bonnet locked but not fully pushed down and no bumper, maybe a bit of water went into the ECU loom/ fuse and relay box. Wouldn't really make send since it seems to only happen at high rpm tho... Will try a few things! Thanks for the reply.
 

hopgop1

ClioSport Club Member
That reminds me of what I forgot to mention, easiest check you can do with the wiring is check the big white connector in the fuse/relay box. Separate it and check for any corrosion, even a small amount can cause issues. It didn't help on mine but it's the first thing everyone says to check before firing the parts cannon.
 

Cliomaxx69

ClioSport Club Member
  Clio 172 2002
Do you know if I should disconnect the battery or is it safe to just unplug it?
 

hopgop1

ClioSport Club Member
I had to remove the battery to get good enough access to the fuse box on mine anyway as I had a huge battery rammed in there at the time. Probably best whipping off the negative terminal to be safe.
 


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