Hi Friends , I have a Punto 1.3 year 2001 , since some time ago the engine lamp start lighning ,

I checked last days with a OBD II reader and got OBD Code P 1135 (Preheeting resistance 1 above Cat) is what my OBD reader indicates,

I figured out by reading here at the forum that it could be the Lambda Sond that is faulty , I started replacing the first ( the one before the cat) without any result the code P1135 still coming back also after cleaning the code, then I also changed the second Lambda sond after the cat and code still comes back , ( after changing the second lambda sond i think that the code P1135 is coming only when the engine is cold , but its keept in the memory ,

I do not have any more idees what can be wrong , for me it sounds like something is wrong with the pre heeting part but i´m not sure,

I should mention that the 2 lambda sonds i changes was universal type 4 wires that i used , ( not original or Bosch)

Can the problem be the Cat ? or are there any other compoments involved for the pre heeting ??

Please advice i´m stocked in how to continue

regards Kostas

Hi Kostas, Welcome to the FF.

Fiat specific code P1135 = "Oxygen sensor heater resistance Bank 1 (Pre-cat)". It doesn't neccessarily mean you need a new sensor. It's never a good idea to just replace the component mentioned in a fault code definition without further diagnosis.

Pre-cat means the sensor before the cat so you didn't need to replace the second sensor. Assuming your new pre-cat sensor is working and you have joined the wires correctly, it's likely that there is a problem with the heater wiring from the sensor.

a cheap copy sensor can be as bad as a faulty one
as said double check the connections referring to the paperwork that came with new one
usually
2 white
one grey
one black
if it came with a real long run in lead sometimes shortening these helps
me?
i always find replacement s/h ones

good luck

http://www.ehow.com/how_4780847_test-oxygen-sensors.html

read part 3 twice to absorb it

Hi again thanks for the answers , I wired the new lambda as the old, the universal hade 2 white cables, one black and one Grey
Exacly the same colours as the ones i replaced.

Does it matter what white cable from the new lambda sond go the white cables in the connector ?

Before replacing the lambda sonds i checked with a Ohm/ voltmeter and between black and grey when heeting up the sond i got 0-0,9 Volts ,
and between the two white wires a had a resistans (Ohm) as well
for both old sonds,

I also tried to swap the pre-cat sond with the after-cat sond but still the same fault P1135 this was done before i changed to two new univers sonds,

can some other compoments like Cat, Map sensor , ECU , or throttle be involved in the fault i have ??

I´m thinking to order one new original lambda sond is that the correct next step for me ??

Regards Kostas

Just couple of thoughts. Did you clear the codes? Is the connector to the lambda clean and silicon greased?

Hi Yes the codes was clean out several times after changing both sonds,

One thing I noticed is if the engine was warm then i did not have the code on my OBD program on the laptop , and sometimes the code was also pending on the laptop but the engine lamp did not ligh

my own confusion is that the code is coming when engine is cold and remain as well when the engine is getting warm

I did not use any silicon grease just mounted the new sonds direcly can this be a problem ???

Any idees what I can try ??


Regards Kostas

Can I messure the resistend on the two white cables on the lambda sond any one that knows what values i should get ??

I´m just thinking if the universal sond differs in term of resistans (Ohm)

//Kostas

http://www.scottnheather.com/audi/pdf/o2sensor.pdf

scroll down to see the wiring for your copy lambda
how do you know you have wired it up right?
you cannot take the old wiring as being wired the same so do the checks i outlined and as i said confirm you have a dammed good earth

a 4 gas check would also confirm if your engine is running correctly

The heat issue isn't about how warm the engine is, but how (or if) the heating part of the lambda is working.

Hi Ok i will double check my wiring on the universal sonds that i mounted

according to the instruktion for the universal sonds the following is stated

2 white cables = pre heating
black = signal +
Grey = signal -

and that is how the original is wired as well according to the link above

what shall i try please help ??

Hi I did some more testing this morning and my 2 old sonds when checking the resistand between the white cables hade a ohm of around 14 the same was on the univeral sonds fitted in the car as well ( white cables as well)

when reading the codes this morning in addition to the P1135 a hade also P1141, after cleaning the codes only the P1135 was pending on my OBD reader ,

the P1141 is O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2) i think ,

Any idees please ,

Can the ECU be faulty ?? or Map sensor or something else ??

Regards Kostas

No indication whatsoever that the MAP is faulty. Or, for that matter the ECU. Clean all contacts, check the wiring from ECU to lambdas.

I still suspect the replacement sensors, though. Scrap yard?

Hi Again

I managed to use FIAT ECU SCAN 3.3 tool and used it
according to this tool I should check the connectors to the white cables and the O2 heater relay ,

when checking via ECU scan 3.0 the pre heating for both sensors get active and suddunly not connected and this changes from pre heter sond to after cat sond over time , so something is strange with the pre heating function (either some connection or if any other components are involved)

I have the codes P1135 and P1141 all the time now

What surprise me is that the P1135 and P1141 refers to a pre heater relay
do you know where it´s located ??

If there is a relay involved i need to find a chack that

anyone that know this ??


thanks for all support and good help

//Kostas

of course if you have a local breaker a replacement loom for the engine bay could be your next step due to old cabling creating problems
have you checked in the ecu for green corrosion?

Pretty sure that someone posted a Mk2 wiring diagram not so long ago. It won't tell you where the relay is, but may give you some clues.

fingers99 said:

Pretty sure that someone posted a Mk2 wiring diagram not so long ago. It won't tell you where the relay is, but may give you some clues.

Click to expand...

it will be a silicone dip in the ecu

Ah, hence green ECU pins............

Hi I found a ECU wiring diagram here at the forum , based on that i will try to follow the cables from the sonds to the ECU , according to the diagram there is a relay involved the question is where its located ,

I will try to do this the following days and post my results,

the Ecu Scan tool is perfect to use ,

thanks and take care

//Kostas

Hi All finally i got 2 original BOSCH lambda sonds , I replaced both to the new ones and cleared the faults with ECU SCAN and everything are OK now ,

A Big thank to all that contibuted with answers on my questions,

the lesson learns is DONT USE Univeral Lambda sonds

thanks and take care ,

//Kostas