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Fiat Punto Cabriolet 1.2 16v 2000 - Emissions failure, electrical load affects O2 sensor #

Posted by Martin Kelly on April 22, 2014, 4:21 pm

Year of Manufacture *: 2000
Engine Size and Code *: 1.2 16v 176B9000
( Optional ) ECU Type: Marelli IAW1BFD.5Z
( Optional ) Scanner Used: Verus
( Optional) Fault Codes: None

Hi

Passes emissions at fast idle and O2 sensor switching normally, at normal idle O2 sensor stuck at 0.8v CO = 1.4%.
If headlights and other electrical loads are turned on then O2 sensor switches normally at idle and emissions are good.
I have run separate earth from O2 sensor grey wire to battery earth but still sticks at 0.8v, no electrical loads on.
Any idea why the electrical load helps here?

Thanks, Martin.

Re: Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor

Posted by Mark Carter <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on April 22, 2014, 7:15 pm, in reply to "Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor"
Mark Carter

Question, what is the electrical load doing to the engine load and how is the ECU adapting to this load.

What testing has been carried out regarding this issue?

Modern cars, Its all wizardry and witchcraft

Re: Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor

Posted by Martin Kelly <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2863' width='330' height='300' border=0 style='border:none;'> on April 23, 2014, 8:55 am, in reply to "Re: Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor"
Martin Kelly

Hi Mark, I understand that the additional electrical load has increased the engine load via the alternator, but as regards how the ECU adapts to this - I don't know.
I realise that that you are trying to let me solve the issue through logical steps (and I appreciate this is a good way to learn) but perhaps another clue?

Regards, Martin.

Re: Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor

Posted by Tommy Forrest <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1706' width='330' height='300' border=0 style='border:none;'> on April 23, 2014, 6:16 pm, in reply to "Re: Fiat Punto Cabriolet 1.2 16v - Emissions failure - electrical load affects O2 sensor"
Thomas Forrest

Hi Martin

Does the idle speed increase when the electrical loads are switched on?

Tommy

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