Check engine light stays on

[Derek Pallet]

I've juIt spent £900 trying to turn off the engine check light new lambda sensors new, maf sensor ,new crankcase breather,now I've been told it could be the secondary air vaccum any suggestions 

[Ahsai]

Do you know what the error codes are/were? There are 500+ error codes that can trip the CEL so we will need some clue.

[Derek Pallet]

The lamda sensors are p0134,p0154 but I don't know the codes for the secondary air vaccum but on my diagnostic it says not passed if that's any help.

[JFP in PA]

8 minutes ago, Derek Pallet said:

The lamda sensors are p0134,p0154 but I don't know the codes for the secondary air vaccum but on my diagnostic it says not passed if that's any help.

 

Welcome to RennTech

 

Both codes are for the interruption of the  sensor signal, which is more often a wiring harness issue rather than a bad sensor.  The diagnostic trees for both codes start with checking the wiring harness, not replacing the sensors.

[Derek Pallet]

They were checked by a porsche fitter when I had the work done he said the wiring seems ok he used 2 of his own to check them 

[Ahsai]

Now saw that you are new member, welcome to Renntech!

 

I only have the 996 diagnostic info but I think they are the same for Boxsters.

P0134 is Bank 1 O2 sensor interruption of signal

P0154 is bank 2 O2 sensor interruption of signal

 

"Not passed" may not mean fail. After the DME has been reset, you need a few drive cycles for all these emission readiness flags to be set. For the SAI readiness to pass, I think the DME needs to verify the SAI at cold start and also when engine is already running. It's possible that you just haven't driven the car long enough for the DME to perform those tests.

 

Are those the only current codes? If there are no other codes, the DME Is not currently complaining about the SAI. Also, there are cases that required many miles of driving before the SAI is set, despite no issues with the SAI system.

Edited March 13, 2019 by Ahsai

[Derek Pallet]

The car is also running very rich I also can't hear any noise from th secondary air vaccum on startup

3 minutes ago, Ahsai said:

Now saw that you are new member, welcome to Renntech!

 

I only have the 996 diagnostic info but I think they are the same for Boxsters.

P0134 is Bank 1 O2 sensor interruption of signal

P0154 is bank 2 O2 sensor interruption of signal

 

"Not passed" may not mean fail. After the DME has been reset, you need a few drive cycles for all these emission readiness flags to be set. For the SAI readiness to pass, I think the DME needs to verify the SAI at cold start and also when engine is already running. It's possible that you just haven't driven the car long enough for the DME to perform those tests.

 

Is the CEL currently ON and if so, can your scanner read the current error codes?

I am not in the car at the moment but will get back to you tomorrow afternoon when I have tried the diagnosis again 

[JFP in PA]

8 minutes ago, Derek Pallet said:

They were checked by a porsche fitter when I had the work done he said the wiring seems ok he used 2 of his own to check them 

 

Sounds like he checked the sensor wiring, he needed to check the wires from the sensor going to the DME as well as the out put voltages and voltage curves.

[Derek Pallet]

I believe he used an ultrasound to check the wiring 

[JFP in PA]

3 hours ago, Derek Pallet said:

I believe he used an ultrasound to check the wiring 

 

I have absolutely no idea what you are talking about.  Wiring is tested using a digital multimeter looking at continuity, resistance, and voltage readings.

[Josephine]

Hi, just joined 13.07.2019.  My (very first Porsche) Boxster 986 (2003) 79,000 miles, 5th owner). keeps lighting up its engine check lamp.  It’s been checked, one dodgy sensor was replaced, but the warning returned.   I have not yet come across  a decisive fix for this common problem, despite hours of reading forums. 

 

I suspect i could be running through a maze of smoke and mirrors here.  All codes seem ambiguous.  Does petrol octane have an effect? The lamp disappeared briefly when I gave it some 98 brew, but it still lit up again after 50 miles. 

 

Has anyone found a solid answer?   What if I have the sensors disconnected.   I hate driving with warning lights blazing, and the solution cannot be found, but further engine problems do not seem a real threat.  My engine performance seems ok, even when the light is lit. 

[Loren]

34 minutes ago, Josephine said:

Hi, just joined 13.07.2019.  My (very first Porsche) Boxster 986 (2003) 79,000 miles, 5th owner). keeps lighting up its engine check lamp.  It’s been checked, one dodgy sensor was replaced, but the warning returned.   I have not yet come across  a decisive fix for this common problem, despite hours of reading forums. 

 

I suspect i could be running through a maze of smoke and mirrors here.  All codes seem ambiguous.  Does petrol octane have an effect? The lamp disappeared briefly when I gave it some 98 brew, but it still lit up again after 50 miles. 

 

Has anyone found a solid answer?   What if I have the sensors disconnected.   I hate driving with warning lights blazing, and the solution cannot be found, but further engine problems do not seem a real threat.  My engine performance seems ok, even when the light is lit. 

 

The check engine light can be used to identify close to one hundred issues.

So you need a Porsche specific scan tool to identify what fault code(s) are showing up. We can help with the fault codes but without them everything would be a guess.

[Josephine]

Thanks you so far, but...

My UK bloke knows what he’s doing, has the unit you mention, it shows “P2096 - Post Catalyst Fuel Trim System Too Lean Bank 1”, he has shown me the clean blank graphs, assures me emissions are normal, changed 1 sensor, and still the lamp comes back.  

 

The code still leaves even the experts guessing because it says no more.   So I could be forking out £60 an hour on a wild goose chase. He hasn’t charged me yet, as it was under a 3 month dealer warranty

 

So...How critical is the sensor, seeing as today I was getting 37mpg at 70mph during a 200 mile drive?

 

Thanks again,

[JFP in PA]

1 hour ago, Josephine said:

Thanks you so far, but...

My UK bloke knows what he’s doing, has the unit you mention, it shows “P2096 - Post Catalyst Fuel Trim System Too Lean Bank 1”, he has shown me the clean blank graphs, assures me emissions are normal, changed 1 sensor, and still the lamp comes back.  

 

The code still leaves even the experts guessing because it says no more.   So I could be forking out £60 an hour on a wild goose chase. He hasn’t charged me yet, as it was under a 3 month dealer warranty

 

So...How critical is the sensor, seeing as today I was getting 37mpg at 70mph during a 200 mile drive?

 

Thanks again,

 

A lean condition does not necessarily mean you have a bad sensor, more likely you have a small vacuum leak or an overly lean cylinder somewhere on that bank, leading to the lean conditions the sensor behind the cat is seeing. A smoke test and reading the spark plug colors should help sort out the problem source.