Check engine light on

[Vali@86]

Hello

I'm new to this forum so sorry if I'm not posting where I should.

Just recently, I've purchased a Skoda Octavia 2.0 (AQY engine code) and after driving it approx. 2.300 km the check engine light came on just the other days.

Now, I should point out the fact that the car still drives ok, but now it has a sort of rough idle (it may vary 20 to 30 rpm on the dash). It can be heard rather than seen and a higher fuel consumption (when idle, the instant fuel consumption shows 2,4 - 2,2 l/h instead of the regular 1,1 - 1,2 l/h)

Also, now around the car you can smell unburnt petrol.

Also I should point out the fact that when I fuelled with a high octane petrol, the light turned off after approx. 1km but came on again after 2-3 km.

Other than that, the car runs ok.

I used a tester to find the error codes and this is what I have found:

 

 

16518 - Oxygen (Lambda) Sensor B1 S1
P0134 - 35-00 - No Activity

17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 35-10 - System too Lean - Intermitent

16555 - Fuel Trim; Bank 1
P0171 - 35-00 - System Too Lean

 

and

 

01039 - Coolant Temperature Sensor (G2)

              30 - 10 Open or Short to Plus - Intermitent

 

 

Now the second one, I don't think it's relevant for the engine light but I thought I should post it anyway.

 

Can you please tell me if this is a clear indication that the lambda sensor should be replaced?

Edited 7 August, 2016 by Vali@86

[Tech1e]

It would appear to be an issue with the pre catalyst lambda probe.

[Vali@86]

This is what I was led to believe after I searched the internet for this error codes. But I still want to be sure.
Can any one tell me where I can download a repair manual for an Octavia with a 2.0 AQY engine?

Also a little update:

I started the car a few minutes ago and after 1 minute it started to make awful smell (like rotten eggs or something) and also small misfires?
Is this a clear indication that the lambda sensor is faulty?

[Tech1e]

If you want to be sure then it needs diagnosis.

[Vali@86]

That's the issue, I don't know how to do that exactly.

This is why I was asking for a repair manual.
First I don't know how to locate the connection for the pre catalyst lambda probe (so I can test it with a multimeter, and I don't know for which values to look out for also) and I don't know exactly where to look and for what values in the VCDS.

The error codes were read by a friend of mine using VCDS software but he does not know how to test a lambda probe.

 

Can you help me with a tutorial or something?

[Tech1e]

The workshop manual won't tell you how to diagnose a fault as such.

We spend years at college and a career in a garage to learn the diagnosis of such issues. Looking at the fault code it's not an electrical issue as such.

See if you can generate a readiness code with VCDS.

[Breezy_Pete]

You can download official repair info via erWin Skoda, it'll cost you a few Euros, but there's a ton of other handy stuff you could download while you're there, including full car data from your VIN number.

Can't you follow the cable coming out of the sensor until you find the connector?

 

workshop-manuals.com may help you locate the connector, if you can put up with all the begging pop-ups.

[Vali@86]

Hi all, thanks for your respons

 

@Tech1e: - I need the workshop manual to help me find the lambda probe electrical connection, from what I can see the wire from the pre catalyst lambda probe goes down towards the underbody of the car. For the diagnostics I found something on workshop-manuals.com:

 

http://workshop-manuals.com/skoda/octavia-mk1/drive_unit/2.0_ltr./85_kw_engine_fuel_injection_and_ignition_system/mixture_preparation_system_electronic_inj.gas/check_for_proper_operation/testing_lambda_probe__g39__and_lambda_control_upstream_of_catalytic_converter/test_sequence/

 

But there are a few things that I don't understand:

 

1 - In the above link it is specified that I should use VAG 1552 tester. Is the information presented there the same as the one I should find if I am using VCDS 15.7 ?

2 - I could not find anywhere the location for the electrical connection of the lambda sensor, can anyone please point out the exact location (I am assuming that is underneath the car since the wire goes down, but I can't see exactly were it goes).

3 - the information from the above link is a little vague. For example it says to test the resistance from the heating element, then voltage supply of the heater and  z19. Should I assume that the heating element is the G39 pre catalyst lambda probe and the Z19 is the lambda probe after the catalyst ?

4 - Where can I find the specified values that I should read from the display groups in the VCDS (I am assuming that this are also found in the workshop manual)?

5 - if the values in the display groups are not meet, then should I test the temperature resistance with the engine off or on ? The same for the voltage supply, engine off or on? Also, should the voltage supply be 12v?

6 - After the above mentioned tests (display values in the VCDS, heat resistance and voltage supply) the link then states that I should turn on the engine (this is why I was asking if the measurements for the heat resistance and voltage supply should be done with the engine off or on, because the values in the display group should be done with the engine on, but after that it does not say if I should leave the engine on or off) and measure the voltage at the wiring loom, but I don't understand which wiring loom is it referring to.

 

@Wino: - thanks for the tip, I also found a workshop repail manula on workshop-manuals.com but as I said above, it's not as conclusive, as for erWin Skoda, I don't wish to make a user account, then use my card account number on online sites, because you can never be too careful

 

As for generating a readiness code with VCDS, I'll buy a VCDS cable with interface and 15.7 software version today (the friend that did the first diagnosis can't help me this week), and will try to generate a readiness code in the upcoming weekend. I am assuming it's not that complicated . Hope I can do it

 

Thanks to both for your reply. Hope that someone can clarify my issues with the above link.

Edited 8 August, 2016 by Vali@86

[Breezy_Pete]

1. Probably similar if not exactly the same

2. You may have to remove some underbody plastic trims to find it.  Info on erWin suggests that connections for both pre-and post-cat sensors are in the same box, but location not specified.

3. Z19 is the heater element within the precat sensor. G39 is the separately named sensing element itself. Both in the same part, in other words.

4. In the relevant erWin document.

5. If there was a specific problem with the heater or the supply to it, you would have a fault code that referenced it, I believe, hence Tech1e's earlier comment "Looking at the fault code it's not an electrical issue as such"

6. They mean the car side of the connector pair where the sensor plugs in. As opposed to the half of the connector that goes to the sensor.

 

"I don't wish to make a user account, then use my card account number on online sites, because you can never be too careful"  Then you won't have access to this excellent resource of information.  Seriously, you buy nothing online with a credit card? I'd consider that quite a bit too careful.

[Tech1e]

VAG 1552 is a very old hand held dealer diagnostic tool, we stopped using that in the late 90s.

[Vali@86]

Thanks Wino, thanks Teche1e for the calrifications.

 

I just bought the diagnostic tool, it came with VCDS 15.7.1 Software.

I'm going to generate a readiness code today and post the results.

Any tips?
I heard that this diagnostic tools are somewhat sensitive. From what I have been told I should only plug it in the OBD connector after the engine was started or after the contact position is at the last position before starting the engine. I should never connect it before I start the engine and/or the contact is not at the last position.

 

@Wino - But since you guys have used erWin Skoda and it's ok, I guess I can give it a shot. I'll look into it tonight.

[PetrolDave]

I just bought the diagnostic tool, it came with VCDS 15.7.1 Software.

 

Worth updating to the latest version, which as of today is 16.8.0

 

Software updates are free for life from Ross-Tech.

[KenONeill]

This is what I was led to believe after I searched the internet for this error codes. But I still want to be sure.

Can any one tell me where I can download a repair manual for an Octavia with a 2.0 AQY engine?

Also a little update:

I started the car a few minutes ago and after 1 minute it started to make awful smell (like rotten eggs or something) and also small misfires?

Is this a clear indication that the lambda sensor is faulty?

The "rotten eggs" smell strongly suggests that you've bought some high sulphur fuel. This is not the fault you're looking for, and can probably be cured by going to a different filling station.

[Vali@86]

Hi all,

 

Thanks to everyone for their reply, here's an update (brace yourself, it's going to be long )

 

I did a couple of test since Wednesday until today, looking through display groups: 030, 031, 032, 033, 034, 036, 041 with fault codes present & deleted and check engine on & off.

I'm going to start with the readiness (I wasn't able to generate a readiness code - if by that you mean the code that is under the set readiness button, mine shows there is no script available, I have the Romanian language version - and the set readiness button is grayed out):

 

Day 1:

Readiness with fault codes deleted (16518, 17536 & 16555) and check engine light off :

Exhaust Gas Regulation:                                              Secondary Air Injection:

- Passed                                                                             - Failed or Incomplete

Oxygen Sensor Heating:                                              Evaporative Emissions:

- Passed                                                                             - Failed or Incomplete

Oxygen Sensor(s):                                                          Catalyst heating:

- Failed or Incomplete                                                  - Passed

Air conditioning:                                                              Catalytic converter:

- Passed                                                                             - Failed or Incomplete

 

Day 2:

 

a) Readiness with fault codes deleted and check engine light off (from day 1):

Exhaust Gas Regulation:                                              Secondary Air Injection:

- Passed                                                                             - Passed

Oxygen Sensor Heating:                                              Evaporative Emissions:

- Passed                                                                             - Failed or Incomplete

Oxygen Sensor(s):                                                          Catalyst heating:

- Failed or Incomplete                                                  - Passed

Air conditioning:                                                              Catalytic converter:

- Passed                                                                             - Failed or Incomplete

As you can see, from day one till day 2, with a couple of km driven and let's say 30 minutes at idle, the Secondary Air Injection went from Failed or Incomplete to Passed.

 

b ) Readiness with fault codes 16518 & 17536  and check engine light on:

Exhaust Gas Regulation:Secondary Air Injection:

- Passed- Passed

Oxygen Sensor Heating:Evaporative Emissions:

- Passed- Passed

Oxygen Sensor(s):Catalyst heating:

- Failed or Incomplete- Passed

Air conditioning:Catalytic converter:

- Passed- Failed or Incomplete

 

Now the Evaporative emisions has also passed

 

Now the results of the display groups:

 

I'm going to post all the results but I would like to start with display groups 032 and 033. Since the 17536 & 16555 fault code reports a lean condition, I thought that it might be a good idea to look especially at this 2 display groups since the show the fuel trim (as I understand, 032 shows long term fuel trim, 033 shows short term fuel trim)

Wish to point out the fact that after deleting the 3 fault codes (16518, 17536 & 16555), only the first 2 reappeared (16518, 17536).

The first one 16518, appears after a short period (approx. 5 min.), the second one 17536, appears after about 10-15 min. or 2-3 km of driving & 5-10 min at idle.

Until today, the only fault code that usualy triggered the engine light was 17536. But today, the EML was triggered by 16518 (which is strange)

 

Day 1:

 

a) Fault codes present (16518, 17536 & 16555), check engine light on:

 

Display group 032:

Adaptation (Idle) Bank 1 Sensor 1: 18.0%                             Adaptation (Partial) Bank 1 Sensor 1: 25.0%

 

Display group 033:

Lambda control Bank 1 Sensor 1: 0.0%                                  Sensor voltage Bank 1 Sensor 1: 0.020V

 

Unfortunately I didn't do this tests as the repair manual indicates (I revved the engine to 2800 rpm)

 

b ) Fault codes deleted, check engine light off:

 

Display group 032:

Adaptation (Idle) Bank 1 Sensor 1: 10.9%                             Adaptation (Partial) Bank 1 Sensor 1: 0.0%

 

Display group 033:

Lambda control Bank 1 Sensor 1: 25.0%                                Sensor voltage Bank 1 Sensor 1: 0.035V

 

Unfortunately I didn't do this tests as the repair manual indicates (I revved the engine to 2800 rpm)

 

 

Day 2 (This time the tests were performed correctly as the repair manual states, with engine at idle):

 

a) Fault codes present (16518, 17536), check engine light off:

Display group 032:

Adaptation (Idle) Bank 1 Sensor 1: 18.0%                             Adaptation (Partial) Bank 1 Sensor 1: 23.4%

Display group 033:

Lambda control Bank 1 Sensor 1: 0.0%                                  Sensor voltage Bank 1 Sensor 1: 0.030V

 

b ) Fault codes present (16518, 17536), check engine light on:

Display group 032:

Adaptation (Idle) Bank 1 Sensor 1: 18.0%                             Adaptation (Partial) Bank 1 Sensor 1: 23.4%

Display group 033:

Lambda control Bank 1 Sensor 1: 0.0%                                  Sensor voltage Bank 1 Sensor 1: 0.000V

 

In none of the above test did the value for Lambda control Bank 1 sensor 1 in display group 033, fluctuated, it either staid flat 0.0% or 25% it never oscillated, as i understand it is normal (https://www.youtube.com/watch?v=yM3iarhSP68#t=31.81833139534884)

Furthermore, today, after I replaced the spark plugs, the same story, flat 0.0% or 25% (it oscillates but in a period of a few minutes)

 

Now for the other disply groups:

 

Display group 030:

 

Day 1 (Unfortunately I didn't do this test as the repair manual indicates (I revved the engine to 2800 rpm):

 

a) Fault codes present (16518, 17536 & 16555), check engine light on:

Status of lambda control upstream of catalytic converter: 100

Status of lambda control downstream of catalytic converter: 010

 

b ) Fault codes deleted, check engine light off

Status of lambda control upstream of catalytic converter: 111

Status of lambda control downstream of catalytic converter: 111

 

Day 2 (test was done correctly, with engine at idle):

 

a) Fault codes present (16518, 17536), check engine light off:

Status of lambda control upstream of catalytic converter: 100

Status of lambda control downstream of catalytic converter: 110

 

b ) Fault codes present (16518, 17536), check engine light on:

 

First time 14:49:

Status of lambda control upstream of catalytic converter: 111

Status of lambda control downstream of catalytic converter: 110

 

Second time 15:52:

Status of lambda control upstream of catalytic converter: 100

Status of lambda control downstream of catalytic converter: 110

 

Third time 14:53: - the values as the second time 100 with 110

 

Display group 031:

 

Day 1 (Unfortunately I didn't do this test as the repair manual indicates (I revved the engine to 2800 rpm):

 

a) Fault codes present (16518, 17536 & 16555), check engine light on:

Lambda actual value - Bank 1: 0.030V                    Lambda nominal value - Bank 1: 0.630V

 

b ) Fault codes deleted, check engine light off:

Lambda actual value - Bank 1: 0.035V                    Lambda nominal value - Bank 1: 0.855V

 

Day 2 (test was done correctly, with engine at idle):

 

a) Fault codes present (16518, 17536), check engine light off:

Lambda actual value - Bank 1: 0.025V                    Lambda nominal value - Bank 1: 0.875V

 

b ) Fault codes present (16518, 17536), check engine light on:

 

First time 14:49:

Lambda actual value - Bank 1: 0.045V                    Lambda nominal value - Bank 1: 0.875V

 

Second time 14:52

Lambda actual value - Bank 1: 0.015V                    Lambda nominal value - Bank 1: 0.875V

 

Third time 14:53:

Lambda actual value - Bank 1: 0.05V                       Lambda nominal value - Bank 1: 0.895V

 

 

Display group 034:

 

Should be noted that none of the tests were completed, although I rev the engine every time for a good 3 to 5 minutes

This are the results for all tests, with & without EML & fault codes:

 

Engine speed: 2640 RPM

Catalytic converter temperature: 360°C

Period of lambda probe upstream of catalytic converter: 0.52 s (this is the only time I saw this value, in all other tests that followed, the value was a flat 0.0s)

Result of a test of lambda probe ageing upstream of catalytic converter: Test ON (stayed on, it never shows the result).

 

Display group 36:

 

The results are pretty much the same in all tests I have done, the Lambda probe voltage downstream of catalytic converter varies in all test, from 0.855, to 0.875, to 0.895 and the Test lambda probe downstream of catalytic converter shows B1-S2 OK

 

Display group 41:

 

The results are the same in all tests I have done:

Resistance of lambda probe heating upstream of catalytic converter: 30.9

Lambda probe heating upstream of catalytic converter: Htg.uC.ON

Resistance of lambda probe heating downstream of catalytic converter: 26.8

Lambda probe heating downstream of catalytic converter: Htg.dC.ON

 

So what do you guys make of all this?

The repair guide says that if values are not meet I should check the heater of the pre cat. lambda sensor, but I don't have the resistance value of the Z19 element in the pre. cat. lambda sensor and for sure I’m not going to pay 7 euros/h on erWin Skoda, it’s way to expencive for me.

The values from the above display groups point towards a lean issue, but I am starting to believe that it’s an O2 issue.

Today I noticed 2 more signs of a rich condition:

• The sparg plugs were black
• The car started to produce black smoke

So the symptoms are this:

- heavy smell (sulfuric, which would indicate, unburned fuel - hydrocarbons)

- rough idle (not visible on the dash, but it can be felt, the dash may show 20-30 rpm jumps)

- you can feel when driving that the engine is running heavy (I don't know how to describe this one)

- sparg plugs were black

- black smoke out the exhaust

- small misfires (they are very weak you can barely hear them)

- O2 fault code: 16518

- Lean issue codes: 17536 & 16555 (this hasn't appeared since I first delete the fault codes).

 

Should I conclude that the lambda probe before cat should be changed?

Edited 13 August, 2016 by Vali@86

[Vali@86]

Hi all,

Problem solved, I've replaced the lambda probe before cat and everything is ok now.

Thanks to all for all your tips and guidance