Stilo fault codes 1684 1687 1220

Hi All,

Can anyone help - my 02 plate 1.6 16V stilo dynamic has fault codes 1684, 1687, 1220 and is in limphome mode. The throttle body has been replaced but made no difference - any ideas?

Many thanks

search stilo tech section as this has been covered many times before

Have looked through tech section and they suggest throttle body replacement-have done this but car won't do throttle re-learn procedure. Car currently in dealer and they have no idea what the problem is!! Any suggestions?

When a throttle learn is carried out examiner shows progress of this operation, ask them what the progress number gets too.

T14086 - Many thanks - will ring them on Monday and ask.

I fear it needs a ECU though

The car developed this fault as we approached a roundabout, came up with engine fault codes 1684 and 1687, limped home, tried a throttle reset then comes up with 1220 throttle relearn fault. Would it be the ECU that failed as we were driving?

Could it be anything to do with the aircon pressure sensor circuit, as doesn't this pull the same voltage as the throttle potentiometer?

have you searched tech section,this has been covered (including AC sensor connector corrosion) although I have seen throttle bodys been changed in most cases its the ECU. (check voltage at throttle body)

What's the damage for a new ECU? Ta 4 all help.

I had a P1687 the other day. "Metering oil pump" = the throttle valve really.
As you can guess, it means the ECU is having trouble understanding the feedback from the TPS (the throttle position sensors) so it will go into limp mode to safeguard the engine. In my case, it was the aircon linear pressure switch which is fed from the same 5v supply, (my fault as I was playing with the air con at the time). Mine was easy to sort out but it shows that a problem on the linear pressure switch can throw out the throttle body circuit too

Anyway, the system is like this

The ECM is your ECU

Your throttle body has two resistance pots or tracks inside which provide feedback voltage to the ECU to tell it where it is. They're different voltage ranges so it can very accurately determine just where the throttle valve is.


Throttle valve motor and pots
See the two potentiometers here? That's what your ECU is having trouble with.
The outputs from these pots look something like this

This isn't a Stilo but it shows the different voltage feedbacks as a throttle is opened and closed
If someone has a scope then you can trace the feedback voltages from the throttle position pots and see if it's a clean and smooth feedback thoughout the full throttle range with no sudden jumps or spikes

Ok Nodding off yet?


Now a bad contact here at the throttle body connector would cause your problems so I'd use some contact cleaner (NOT WD40 but proper electrical contact cleaner) on the connector



Then I'd get up the other end at the ECU and recheck the connections and some more cleaner there to freshen up the contacts and, of course, check the ECU earths

Again, someone with a scope could check the output voltage from the ECU and what's actually feeding back to the ECU from the TPSs before condemning the ECU. It could well be the ECU that has a problem but it can only go on the information it's given from the throttle body

P1687 means :
"interruption of selflearning (throttle body) due to incorrect environmental conditions / out of tolerance "
so it really has a relationship with the throttle body.

yellowstilo

I thought I said that in the first line
" I had a P1687 the other day. "Metering oil pump" = the throttle valve really".

Many thanks Deckchair5 - how did you sort out your air con linear transducer problem?

Ha! It was me that was the problem, I was just being clumsy and shorted the contacts