996 Carrera 3.4 Lambda fault code

[towny]

Can anyone help?

I know there have been several posts on this

I have the following fault codes

P1602 Supply voltage Open circuit

P0131 O2 sensor ahead of cat. conv. Cylinder (1-3)

P0151 O2 sensor ahead of cat. conv. Cylinder (4-6)

P1115 Heating power O2S ahead of cat. c. bank 1

P1119 Porsche fault code Heating power O2S ahead of cat. c. bank 2

I have replaced both Lambda sensors but the fault codes are still been thrown up

I’m getting a constant Lambda reading of 1 and a minus voltage reading on both sensors

Is this correct

Loren has replied to a previous post to check the following

Things to check:Short circuit in signal wire to ECM ground or housing ground.Short circuit in signal wire to ECM ground or housing ground.DME control module output stage short to ground.Possible causes:- Wiring harness- Oxygen sensor- DME control module

According to the explanation of the codes it’s a Type 3 Short to ground/below lower limit/lean mixture threshold

My question is how do I test for the above?

I would be grateful for any guidance

[Loren]

Ignore the P1602 - you get that error whenever the battery has been disconnected.

Very odd to have both before cat sensors fault at time with the same fault. Have you checked to see that they are getting power? and not shorted?

Check oxygen sensor

1. Remove H02S connector 1 ahead of catalytic converter.

2. Connect ohmmeter on pin side to pin 3 and to H02S housing. Display infinite ohms.

3. Connect ohmmeter on pin side to pins 3 and 2. Display infinite ohms.

4. Connect ohmmeter on pin side to pin 4 and to H02S housing. Display infinite ohms.

5. Connect ohmmeter on pin side to pins 4 and 2.Display infinite ohms.

Check wiring harness

1. Remove all four H02S connectors.

2. Switch on the ignition.

3. Connect voltmeter at sleeve to pins 3 and 4 of H02S connector 1 ahead of catalytic converter.

Display - approx 450 mv.

4. Connect voltmeter at sleeve to pin 3 and ground.

Display - approx 720 mv.

If the measurement according to items 3 and 4 does not show the specified values, remove DME control module connector and check wiring for short to ground.If no short to ground can be detected, you may need to replace DME control module.

Either way clear all the codes after testing or correction and see if any come back.

[towny]

Thanks Loren

Carried out the checks and the readings seems to be fine infinite ohms and 456mv and 717mv

But still getting P0131 and P0151 codes

Any further thoughts

[Loren]

When you replaced the sensors did you use Porsche sensors or after market?

[towny]

they are after market

[Loren]

Well, you will likely need to check the specs very closely as many after market sensors do cause problems.

Porsche OEM or Bosch (exact) OEM replacements should work.

[towny]

thanks for the info