Fuel Trim; Bank 1: System Too Rich

[johnone]

Hi all,

Just wondering if anyone has encountered these two DTC's before:

16485 - Mass Air Flow Sensor (G70): Implausible Signal

P0101 - 35-00 - -​

16556 - Fuel Trim; Bank 1: System Too Rich

P0172 - 35-10 - - Intermittent​

ESP light on

After 4 or more starts with ESP light on - CEL comes on


A brief background - Early December (6th) I replaced the MAF due to similar codes and the ESP (traction control) light on.

All was well for a few weeks until these codes appeared:

16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit

P0130 - 35-00 - -
16485 - Mass Air Flow Sensor (G70): Implausible Signal

P0101 - 35-00 - - Intermittent​

16556 - Fuel Trim; Bank 1: System Too Rich

P0172 - 35-10 - - Intermittent​

16556 - Fuel Trim; Bank 1: System Too Rich

P0172 - 35-10 - - Intermittent​

This time I checked for vacuum leaks and found a split in the brake servo hose - right next to the master cylinder.

So I ordered a complete new brake servo hose (2 parts) and replaced.

All was well for 2 days and now I get the above codes (P0101 & P0172) with the ESP light on.

Any ideas?

Thanks​

 

[thorsy22]

System too rich code is likely to bring on the engine light, possibly the maf fault too.
Replace the MAF with a genuine Audi/Bosch one and should clear those 2 fault codes. As for the ESP light, are you sure it's not disabled as there is no fault codes relating to that system.
Have you tried clearing all dtc's?

Edit: You say you replaced the MAF was it a cheap ebay one or a "proper" one?

 

[rusty s3]

esp light comes on when maf is unpluged and engine is started.check the maf plug and wiring to the plug.
this would also bring up these codes.may well be a faulty maf?

 

[johnone]

Yeah I replaced the Hitatchi MAF with a genuine WV/Audi Hitatchi 06A 906 461B MAF - £100
It is definitely connected correctly.

The ESP light comes on as a result of the ECU detecting a rich running condition - I imagine to reduce power and protect the engine from damage?

I think the next step is to do a full log of blocks 003 / 031 / 032 from cold to running temp to see what the values are for the MAF and Lambda sensors.

I did run a quick log yesterday on tick over - cold and measuring block 031:

TIME  	Lambda 	Lambda 
STAMP	Current   Specified


248.73	1.999 	0.998
250.16	0.9971	0.9971
251.47	0.9844	0.9971
252.8 	0.957 	0.998
254.3 	0.9941	0.9971
255.71	0.834 	0.9971
257.08	1.999 	0.9971
258.51	0.9482	0.9971
259.88	0.9346	0.9971
261.2 	0.9033	0.9971
262.57	1.999 	0.9971
263.88	1.999 	0.998
265.08	0.9268	0.998
266.51	1.999 	0.9971
267.85	0.8496	0.9971
269.28	0.9824	0.9971
270.59	1.999 	0.998
271.84	0.8467	0.9971
273.02	0.8535	0.9971
274.3 	0.918 	0.9971

I guess at -6 oC you could expect a value of 1.999 for lambda on choke!?? But I doubt it.
I think when I get to run a full test with logging - it may show the front O2 sensor is at fault.

 

[Welly]

Yeah I replaced the Hitatchi MAF with a genuine WV/Audi Hitatchi 06A 906 461B MAF - £100
It is definitely connected correctly.

The ESP light comes on as a result of the ECU detecting a rich running condition - I imagine to reduce power and protect the engine from damage?

I think the next step is to do a full log of blocks 003 / 031 / 032 from cold to running temp to see what the values are for the MAF and Lambda sensors.

I did run a quick log yesterday on tick over - cold and measuring block 031:

TIME  	Lambda 	Lambda 
STAMP	Current   Specified


248.73	1.999 	0.998
250.16	0.9971	0.9971
251.47	0.9844	0.9971
252.8 	0.957 	0.998
254.3 	0.9941	0.9971
255.71	0.834 	0.9971
257.08	1.999 	0.9971
258.51	0.9482	0.9971
259.88	0.9346	0.9971
261.2 	0.9033	0.9971
262.57	1.999 	0.9971
263.88	1.999 	0.998
265.08	0.9268	0.998
266.51	1.999 	0.9971
267.85	0.8496	0.9971
269.28	0.9824	0.9971
270.59	1.999 	0.998
271.84	0.8467	0.9971
273.02	0.8535	0.9971
274.3 	0.918 	0.9971

I guess at -6 oC you could expect a value of 1.999 for lambda on choke!?? But I doubt it.
I think when I get to run a full test with logging - it may show the front O2 sensor is at fault.

Do some logging, that's all over the joint. I would imagine that 1.999 is the maximum possible value so I would suspect the Lambda is fried.

 

[johnone]

Hi all,

Got a chance to go for a drive today and get some logging done for measuring blocks 003 / 031 / 032.

To start I cleared the existing fault codes in Engine and ABS controllers.

Setup logging and went for a 30 min drive - in varying traffic conditions - with a burst on the dual carriageway.

Everything was running perfectly until around the 23 min mark (3/4 along the graph) when having set off from some traffic lights the ESP / Traction Control light came on.

Having looked through the logged data - a rich condition was encountered with a 0.79 Lambda value at 1436.81 (Time Stamp)

However, I am still at a loss as to the cause of the fault!

The Fault codes logged were as before:

16485 - Mass Air Flow Sensor (G70): Implausible Signal
P0101 - 35-00 - -
16556 - Fuel Trim; Bank 1: System Too Rich
P0172 - 35-10 - - Intermittent

I have attached graphs for different measuremets:

Lambda Current vs Specified

Lambda Adaptation Values

Air Mass

Engine Speed

To me the Lambda values seem extreme - does anyone else get lambda values of 1.999 in group 031?

I can only think that the Pre Cat Lambda sensor is on its way out!

Any help is much appreciated!!!

Cheers

 

[badger5]

intake airmass has a max scale of 80g/s? do I read that right?
oh hang on, this is a 1.6 engine?

presuming the blocks are the same.. Not plugged into a 1.6 I can think of..
block 001 would be pegged at -25% fuel and block 032 fuel trim would be pegged at an equally large negative number I would guess if it thinks its too rich and has been pulling fueling out..
IF this is actually the case and not a false sensor reading, then I have seen this once before and it was a blocked fuel pressure regulator which could not regulate the pumps pressure to 3bar..

just a thought

 

[johnone]

Yeah its a 1.6 8v BFQ.

MAF was replaced only a few weeks ago - and it is consistent with the engine speed on the charts below.

Blocks 032 measure Lambda (Idle) Self-Adaptation and Lambda (Partial) Self-Adaptation respectively.

Both of which register a value of 0 - with Lambda (Partial) Self-Adaptation decreasing from 0 to -0.4 / -0.8 / -1.2 / -1.6 over a 30 min run.

Should the pre cat sensor be reporting back values of 1.999?

Thanks for the info BTW.

 

[badger5]

on steady cruise precat lambda should be 1.00, on overrun yes it will go 1.999 off scale lean as injectors are switched off on overrun.. but only on overrun... cruise should have some activity
block 001 shows the instantaneous lambda correction so look at this under steady cruise..

 

[johnone]

Quick update...

Issue seems to be resolved - Thinking it may be the lambda sensor that is at fault (possibly dirty) I purchased a can of CataClean CataClean Global Ltd..

Having put this through my tank - 10 / 15 mile drive - I am happy to report no further DTC's have appeared!!!


I did take a log of block 001 which ranged from -14.1 to 17.2:

Engine Speed:

Lambda Current vs Specified:

Group 032 Lambda (Idle) and Lambda (Partial) Self-Adaptation values are 0.8 and -0.4 respectively.

I think the pre/post cat sensors may have been reporting inaccurate values and the ECU has been adapting incorrectly.

Thanks for your help! :thumbsup:

 

[johnone]

Hi All,

It seems the problem has not been resolved!
Got the following DTC's this morning after about 5 mins of driving:

16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
P0130 - 35-10 - - Intermittent
16485 - Mass Air Flow Sensor (G70): Implausible Signal
P0101 - 35-10 - - Intermittent
16556 - Fuel Trim; Bank 1: System Too Rich
P0172 - 35-10 - - Intermittent

I am starting to think its the front O2 Sensor - I hope its not tho - nearly £100 to buy and a pain in the backside to replace!

Any ideas on things to check?

Thanks

 

[johnone]

UPDATE: happened again this morning after 5 mins of driving!!! :-(

 

[s3gazz]

Hi all,

Got a chance to go for a drive today and get some logging done for measuring blocks 003 / 031 / 032.

To start I cleared the existing fault codes in Engine and ABS controllers.

Setup logging and went for a 30 min drive - in varying traffic conditions - with a burst on the dual carriageway.

Everything was running perfectly until around the 23 min mark (3/4 along the graph) when having set off from some traffic lights the ESP / Traction Control light came on.

Having looked through the logged data - a rich condition was encountered with a 0.79 Lambda value at 1436.81 (Time Stamp)

However, I am still at a loss as to the cause of the fault!

The Fault codes logged were as before:

16485 - Mass Air Flow Sensor (G70): Implausible Signal
P0101 - 35-00 - -
16556 - Fuel Trim; Bank 1: System Too Rich
P0172 - 35-10 - - Intermittent

I have attached graphs for different measuremets:

Lambda Current vs Specified

Lambda Adaptation Values

Air Mass

Engine Speed

To me the Lambda values seem extreme - does anyone else get lambda values of 1.999 in group 031?

I can only think that the Pre Cat Lambda sensor is on its way out!

Any help is much appreciated!!!

Cheers

that nothing mate my car just failed mot coz i got that reading at 5.400 should of been 0.300 my must be totaly fried lol

 

[johnone]

Hi All,

Found the issue - Vacuum hose from just before the throttle body to the intake manifold was off!

Shoved it back on and all is well!!!

I guess the DTC's were correct and did point me in the correct direction.

MAF error recoded due to un-metered air being drawn in to the system and consequently implausible values being generated.
Rich running condition detected as the ECU compensates for the un-metered air.
Lambda error due to the additional air and compensation with fuel mixture.

 

[s3dave]

Well done, glad your sorted...

 

[Nilz]

Nice one mate, glad you got it sorted, these ****** vacuum and boost leaks cause no end of trouble for us dont they!!!

 

[johnone]

-- Update --

This error tuned out to be a clogged throttle body.

I had the car booked in at a Garage in the Wirral called Discount VW Audi - Very good service!

This cleared the errors and the ASR & Engine Management light have been off.

 

[Welly]

Happy days, glad it's sorted. Vac hoses on NA cars are a right pain - I remember those days, and don't miss them.

Now I have vac hoses on turbo motors instead.... Yay....

 

[Jaggt]

Hi, I know this is an old thread but wonder if anyone could help. I have the exact same problem with our beetle which I believe has the same engine. What program are you using to log this data and where could I get it from.
Our car also smokes quite badly when stuck in stop start traffic for more than 10 minutes, but is ok again once under way?!? Wonder if it's related?
I've cleaned out the throttle body already, when I replaced the intake pipe (£95 from the main stealer!) which had a crack in and was hoping this was the cause. Have recently changed the O2 sensor, maf sensor, coolant temp sensor and many other bits but still have the same issue.
Please, somebody help!
Many thanks in anticipation.
James.

 

[[Dave B]]

What year is the car?

 

[Jaggt]

It's a 2001

 

[[Dave B]]

Check the FPR isn't clogged, mine was which caused the code and rich running in my car,although it didn't cause smoking. I expect they were using VCDS to log the values.

 

[Jaggt]

Thanks for the reply. I have checked the regulator. Looked clean but will check again.
Yes the smoking is a real mystery. Just hoping it's not more serious than a vacuum leak.
Do you know where I can get vcds? And does it require any special leads?
Cheers

 

[sinbrad]

Hi, I know this is an old thread but wonder if anyone could help. I have the exact same problem with our beetle which I believe has the same engine. What program are you using to log this data and where could I get it from.
Our car also smokes quite badly when stuck in stop start traffic for more than 10 minutes, but is ok again once under way?!? Wonder if it's related?
I've cleaned out the throttle body already, when I replaced the intake pipe (£95 from the main stealer!) which had a crack in and was hoping this was the cause. Have recently changed the O2 sensor, maf sensor, coolant temp sensor and many other bits but still have the same issue.
Please, somebody help!
Many thanks in anticipation.
James.

Did you resolve this issue as my missus has a beetle doing the same and its driving me nuts (and she is)...