2002 Audi A4 16804 Efficiency below threshhold

Bought a 2002 Audi A4 1.8t (AMB) Quattro with tiptronic. Head was warped and breather hoses/vacuum lines were a mess.

Rebuilt head and straightened out all the vacuum lines, check valves etc.

After everything was straightened out, had 2 codes coming back consistently.

Address 01: Engine Labels: 06B-909-518-AMB.lbl
Control Module Part Number: 8E0 909 518 F HW: 8E0 909 018
Component and/or Version: 1.8L R4/5VT G 0003
Software Coding: 0016751
Work Shop Code: WSC 63351 000 00000
VCID: 336E048F518479A6B3-515A
3 Faults Found:

18057 - Powertrain Data Bus
P1649 - 008 - Missing Message from ABS Controller
17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 001 - System too Lean - Intermittent - MIL ON
16804 - Catalyst System; Bank 1
P0420 - 002 - Efficiency Below Threshold

Readiness: 0000 1101

ABS controller was out getting rebuilt and has since been reinstalled and cleared.
Group 32 was showing +25% on Adaptation (Partial) and a run to reline showed the MAF not getting more than 90g.
Replaced MAF with Bosch unit part # 0280218063 which matches unit in car originally.
Code 17536 is now gone.

Now only remaining code is 16804

I have a screen shot of Measuring blocks but cannot figure out how to paste here

Info from engine group on screen shot is as follows:

Group MB1 MB2 MB3 MB4
032 0.0% 9.4%
034 800/min 485C 1.632 B1-S1 OK
043 800/min 555C 0.245 V B1-S2 OK

I monitored these for an hour today and the Adaptation (Partial) would float between 9.4% - 15% and the Catalyst temp between 555C and 645C
I did look at the catalyst through the front O2 sensor hole and it looked intact. The front O2 had a white coating that looked like powder. Similar to a spark plug when running lean. I cleaned off what I could.

Just trying to determine what step to take next. Don't mind replacing parts, just want to replace the right ones.

Verify the fp and filter plus regulation is a known issue as well as maf issues.
Firmware update is needed.
I can help with parts and update programming ....just let me know.

Hi. I would suggest that given the pervious engine fault the cat is now failing. If you can scope test front and rear O2 sensors
At 2000 rpm with cat hot and the rear sensor has any switching following the normal activity of the front then you will get P0420.
If you can't scope test then a gas analyser again engine at cruse 2000rpm. If you get a calculated lambda value of 1 Then the cars running correctly and the co will be low. Maybe low enough
to pass an emissions test but if you are still getting P0420 the cat is still not efficiant enough to pass its own test of rear lambda sensor activity.

I have had an a4 where the cat was replaced three times in two weeks with after market cats from two different manufacturers
All would pass the emissions test but all were not good enough to stop the rear sensor switching a bit causing code p0420 after a test drive.
May be after a drive cycle or two.
Fitted dealer cat and fault gone.
That was after new Europe type approval standards had been introduced for cats. As there had been lots of poor quality after market ones available and they are still not any where as good as oe.
So if jack says a software update may fix this then maybe the code setting criteria has been altered.

Running in closed loop with good fuel trim values If the cat is really bad the you will see the rear sensor switching on vcds, again more likely at higher engine speeds

Also antifreeze will destroy a cat.
Hth Alan.

Address/Correct lean condition "first" and wake up the OXS.........then do the rest.

From Audi TSB 2013801

Vehicles with engine control module (J220) SW Part Number 8E0 909 518 F or 8E0 909 518 G must be updated to SW Part Number 8E0 909 518 F or 8E0 909 518 G SW Level 0005 or higher.

Update the Engine Control Module (J220), address word 01, via SVM using SVM Action Code: NA8E24JV01.

Click to expand...

Your car:

Address 01: Engine Labels: 06B-909-518-AMB.lbl
Control Module Part Number: 8E0 909 518 F HW: 8E0 909 018
Component and/or Version: 1.8L R4/5VT G 0003

Click to expand...

0003 < 0005

Also, please post the FULL Auto-Scan.

B1S1 is at 1.6v so i would think it is a wide band sensor. if so then there wont be much variation from that you will have to look at the lambda eqiv values
and the current demand from the sensor to see its activity. if it will show amps and eq values responding to rich or lean alterations and the
systems is in closed loop then the cat should be working correctly.
the fuel trim values are lean but not out of range. what was the engine speed when looking at fuel trim.

Basics should not be circumvented.........
Firmware update and known issues for FP and fuel volume + regulation need to be measured first ........and before anything else.

Thanks everyone for all the replies.

FWIW, the lean condition is gone since installing the new MAF

Sorry I forgot to mention that I did check fuel pressure and reading 50-55 PSI at the fuel rail.

Readings were taken running 60-70 MPH and 2500-3000 RPM

Than firmware update it is .............

Have been traveling the last 4 weeks and no time to look into this until yesterday. This what I have currently:

Address 01: Engine Labels: 06B-909-518-AMB.lbl
Control Module Part Number: 8E0 909 518 F HW: 8E0 909 018
Component and/or Version: 1.8L R4/5VT G 0003
Software Coding: 0016751
Work Shop Code: WSC 63351 000 00000
VCID: 336E048F518479A6B3-515A
2 Faults Found:


17536 - Fuel Trim; Bank 1 (Mult)
P1128 - 001 - System too Lean - Intermittent - MIL ON
16804 - Catalyst System; Bank 1
P0420 - 002 - Efficiency Below Threshold

I thought the lean CEL had been corrected. I know I need to update the software version from 003 to 005. Local dealer really didn't know what I was talking about.

I have replaced the fuel filter with a VW unit. No change.

Jack, I have sent in a request to your shop to get the cost

Affirmative I have responded........Thank you!

More info.

Checked aux vacuum pump last night via VCDS and status came back OK.
Checked fuel flow and am getting 138 ltrs/hr. I looked for spec in Bentley manual but could not find it. Must have looked in the wrong place. Anyone know what a stock fuel pump should flow with a 2002 A4 with 1.8t Quattro?

As a follow up, found the problem with the turbo intake pipe. PO had "engineered" a way to install one of the lines coming off the TIP which I looked over many times (black hose on a black hose) which was allowing unmetered air into the system.

Thanks for all the advice

Rebuilt head and straightened out all the vacuum lines, check valves etc.

Click to expand...

FOD strikes again!

I just installed a Bosch wideband o2 sensor on my Jetta 2.5 and now get the engine light. Does computer adjust settings automatically or do i need to set new parameters? I'm getting the 16804 fault code.

Pinpointdiag said:

B1S1 is at 1.6v so i would think it is a wide band sensor. if so then there wont be much variation from that you will have to look at the lambda eqiv values
and the current demand from the sensor to see its activity. if it will show amps and eq values responding to rich or lean alterations and the
systems is in closed loop then the cat should be working correctly.
the fuel trim values are lean but not out of range. what was the engine speed when looking at fuel trim.

Click to expand...

Hello William,

Please post an auto-scan..........

I just installed a Bosch wideband o2 sensor on my Jetta 2.5 and now get the engine light. Does computer adjust settings automatically or do i need to set new parameters? I'm getting the 16804 fault code.

Click to expand...

http://forums.ross-tech.com/showthr...nter-O2-sensor&p=114425&viewfull=1#post114425

16804/P0420/001056 - Catalyst System; Bank 1: Efficiency Below Threshold Possible Causes

• Leakage in Intake and/or Exhaust System
• Catalyst faulty
• Oxygen Sensor(s) faulty
• Oxygen Sensor(s) Control faulty

Possible Solutions

• Check Intake and Exhaust System for Leaks
• Check Catalyst
• Check Oxygen Sensor(s)
• Check Oxygen Sensor(s) Control
  • Perform Oxygen Sensor(s) Aging Check

Click to expand...

JPPSG
http://forums.ross-tech.com/showthr...essional-Problem-Solver-Guide-quot-JPPSG-quot