ECU Wiring issues?

[bigyinuk]

Hi all.


I'm still struggling to fix this Lambda sensor issue (P0134) with my daughter's Peugeot 206 1.4 petrol 2004 w/ Sagem 2000 ECU

Its NOT the sensor - I've now fitted 2, (the first replacement was itself faulty and caused a different error).

I can measure the sensor voltage both at the sensor and both sides of the 4 pin connector, it varies but is 200mV - 900mV typically. So broadly similar to what I see on the downstream sensor.

Sometimes you can see this on the engine parameters section on Planet.

I look at the two Oxygen sensors (upstream and downstream) and take a note of the voltages, whilst simultaneously watching the upstream sensor's voltage on my multimeter.

Its an intermittent fault, sometimes the Upstream sensor shows a steady unmoving 450mV on the diagnostics but is reading around 800mV (changing up and down) on the sensor - the ECU just isn't seeing the sensor at all times.

So this indicates to me a wiring / connector fault.

I took the connectors out of the ECU and put them back and that *seemed* to fix it for a while.

Also just appeared is P0122 Throttle position sensor low stop - Maybe coincidental, maybe not.

I've tried the BSI reset procedure etc.

My guess is that there is either:

(a) Break in the wiring between sensor and ECU plug.
(b) Bad connection in the plug that goes in the ECU.
(c) Dry joint actually in the ECU or faulty ECU (scary prospect faulty ECU).

Anyone seen this type of issue? Are the Sagem ECU's reliable? What's the most likely culprit ?

Hope someone replies

Thanks all

Jon

[CitroJim]

Jon, check earths everywhere you can...

My 207 had a long history of electrical 'funnies' including the problems you have. I've known the car almost since new - it was my ex's and then my eldest daughter's - and it was always troublesome...

After symptoms intensified and it almost killed my daughter I took custody of the car - now called Christine - and found the problem...

A buff bodyshell earth... The one where the battery negative initially bonds to the bodyshell before going on to the gearbox. I'm not saying that is your problem but it's worth checking that and all other earth lugs/tags...

[bigyinuk]

It *is* the "X" connector, the one nearest the bulkhead. Wiggle it even slightly and the engine will rev. I've cleaned connections, tightened the fit of the plugs but it still does it, although not as bad as it did. Next step will be to take the connector apart and check the crimps. If I can get a new connector I'll splice it on to the cable.

Need someone breaking (or preferably scrapping) a petrol 206.

Looms are available on eBay but I'd prefer to keep the repair as cheap as possible as I have to eat as well as keep daughter's car on the road

[CitroJim]

It *is* the "X" connector, the one nearest the bulkhead. Wiggle it even slightly and the engine will rev.

Well found

Do you have a picture of this connector?