O2 harness flaky? CEL with new ECU and O2 sensor.

[pugface]

2006 Cayenne Turbo S   -              214,000 miles

 

Hi all, I am trying to chase down some CELs and rough running.

A little history - all O2 sensors replaced in 2016

03/2018                P2629    - shop cleaned up harness, CEL went away

12/2020                P2629   shop replaced sensor

09/2022                P0050    shop replaced sensor

10/2022                P0050    ECU swap

10/2022                Sensor replaced in case it was faulty

10/2022                CEL came on, this  time I cleaned up the harness myself

12/2022                P2629    P2247 P2A03 - cleaned up harness

05/2022                P0431, P0155, P2A03

06/2022                Car went to shop for something else, they saw the problem, but on reconnecting the battery, it was OK again

06/2022                CEL came on way home from shop ☹ P2189 P0150

 

I cleared the codes again, drove it yesterday, it started to idle very roughly and shudder on acceleration.

Drove into town again today, the CEL came back, now with a bunch of codes

 

P1133 P2179 P2189 P0150

along with

P0300 and P0307 misfires

 

This is all looking like Bank 2 sensor 1. That is the driver’s side upstream, correct? The 6-wire plug?

 

With the multiple sensor swaps, and the ECU swap, I would think the logical suspect is the harness.

 

Does anyone know where the sensor wires end up on the ECU side? I’m thinking I should ring all 6 wires out on a meter and make sure the harness is OK

 

Any other ideas?

Thanks,

pf

[pugface]

Shoot, I meant to explain this part better:

In Sep. 2022, I had the P0050 code, and my local shop replaced the sensor. The code came right back, they hypothesized that the problem was on the ECU end, said might not be worth the cost to fix. I sourced an ECU from eBay, and had my existing ECU cloned to it. When I installed the clone ECU, the CEL came right back again. This time the shop warrantied the sensor and replaced it again. On my way home from that, the CEL came on again!

[Loren]

Did anyone try to reprogram the ECU?

I would certainly do that before buying a new or used ECU.

[pugface]

10 hours ago, Loren said:

Did anyone try to reprogram the ECU?

I would certainly do that before buying a new or used ECU.

Thanks for the reply!

I don't think so. Honestly I'm much more familiar with non-automotive electronic control systems (my day job) than fixing cars. Is this basically re-flashing the program memory of the ECU? I don't think that has happened. Is that a dealer-only thing? Used ECU is actually very cheap, probably because they are one of the easiest things for a dismantler to remove and they don't seem to break very often.

The working theory was that one of the inputs on the ECU module went bad, so I swapped with a known good one - or at least close to "known good". It did work fine for several months. Since I've swapped the ECU and the O2 sensor, I was leaning towards the wiring harness. 

[Loren]

Yes, it is basically re-flashing the program memory of the ECU. Certainly worth a try.

 

Each ECU must be programmed to the car - no straight swaps.

[pugface]

On 6/17/2023 at 10:25 AM, Loren said:

Each ECU must be programmed to the car - no straight swaps.

Thanks Loren

When I got the extra ECU, I sent it and my original out to a service that clones the entire ECU - VIN and immobilizer data too, so I now have 2 identical ECUs that can be swapped. Can I ask why you suspect the ECU and not the harness?

 

Thanks

Sam

 

[Loren]

Well if they cloned an ECU that had a loss of program memory then your second ECU is likely to also have that same loss.

When you re-program the ECU from a PIWIS tester get the whole program re-written to the ECU - plus any bug fixes Porsche has found.

[pugface]

Thanks, I'll see if my indie can do it