View Full Version : Extreme limp mode; can't go past 1000 RPM

04-04-2017, 05:18 AM
I was out driving the other day and noticed the EPC light turned on. After about half an hour the car suddenly lost nearly all power - I was not able to rev the engine past about 1000 RPM, limping my way to a place where it was safe to stop. After opening the bonnet I heard a clicking sound, which seemed to come from the top of the air filter box, besides the MAF connector. It looked like the sound was coming from a relay or something on top of that box. After turning the car off and on again, it seemed fine, though the EPC light was still on, and I drove it very carefully trying not to rev it or engage the turbo and I made it home.

Does anybody know what might be the matter and how to fix it?

(CEL did not turn on)
A4 1.8T Quattro 2000 ANB

04-04-2017, 08:34 PM
Maybe it's you're ICM Ignition control module. If it's mounted on top of you're air filter box.

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04-05-2017, 04:28 AM
If it has an EPC light, it doesn't have an ICM. They are mutually exclusive on the B5. The clicking noise was from the N80 Evaporative Emissions purge control solenoid valve. It is supposed to click. That is it's job.

For the limp mode and EPC light: likely there is a problem with the crankshaft position sensor (aka: "crank sensor" or "RPM sensor" or "engine speed sensor"), or a problem with the electronic throttle (either the accelerator pedal sensor or the throttle body).

In this case, there will most definitely be a specific code stored which will quite likely tell you exactly where the fault is. A generic OBD2 scan tool might pick it up, but I recommend using VCDS or VCDS-Lite so you see all the intermittent codes.

04-05-2017, 05:41 AM
Thank you; I can get access to a cable and the proper software and post the codes.

04-06-2017, 05:22 AM
Good lord. Here's the log from VCDS (after clearing and rerunning):

VCDS-Lite Version: Release 1.2
Thursday, 06 April 2017, 14:09:05:

Chassis Type: 8D - Audi A4 B5
Scan: 01,02,03,08,15,16,17,25,35,37,45,55,56,57,67,75,76 ,77

Address 01: Engine Labels: Redir Fail!
Controller: 4B0 906 018 AL
Component: 1.8L R4/5VT G 0002
Coding: 05201
Shop #: WSC 00000
8 Faults Found:
16795 - Secondary Air Injection System: Incorrect Flow Detected
P0411 - 35-00 - -
17931 - Crash Signal from Airbag Controller: Implausible Signal
P1523 - 35-10 - - - Intermittent
17513 - Oxygen (Lambda) Sensor Heating; B1 S2; Heating Circuit: Short to Plus
P1105 - 35-10 - - - Intermittent
17579 - Angle Sensor 2 for Throttle Actuator (G188) Implausible Signal
P1171 - 35-10 - - - Intermittent
17950 - Angle Sensor 1 for Throttle Actuator (G187): Implausible Signal
P1542 - 35-10 - - - Intermittent
16497 - Intake Air Temp. Sensor (G42): Signal too High
P0113 - 35-10 - - - Intermittent
17987 - Throttle Actuator (J338): Adaptation Not Started
P1579 - 35-10 - - - Intermittent
16891 - Idle Control System RPM: Higher than Expected.
P0507 - 35-10 - - - Intermittent
Readiness: 0000 0000

Address 15: Airbags Labels: 8D0-959-655-AI8.LBL
Controller: 8D0 959 655 J
Component: Airbag Front+Seite 1001
Coding: 00104
Shop #: WSC 06325
VCID: 3D0DBAF72469
2 Faults Found:
65535 - Internal Control Module Memory Error
00-10 - - - Intermittent
00532 - Supply Voltage B+
07-00 - Signal too Low

Address 35: Centr. Locks Labels: 8D0-862-257.LBL
Controller: 8D0 862 257 C
Component: ZV-Pumpe D12
Coding: 00001
Shop #: WSC 06335
VCID: 2D2D8AB7F409
3 Faults Found:
01367 - Central Locking Pump Run Time Exceeded (Likely Leak)
35-00 - -
01361 - Switch for Anti-Theft Alarm; Close
29-00 - Short to Ground
01365 - Lock/Unlock Switch; Interior
29-00 - Short to Ground

Address 17: Instruments Labels: 8D0-959-655-AI8.LBL
3 Faults Found:
01039 - Coolant Temperature Sensor (G2)
30-10 - Open or Short to Plus - Intermittent
00779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
00562 - Sensor for Oil Level/Temperature (G266)
27-00 - Implausible Signal

When I turned on the ignition today, it was as if the instrument clusters could not get enough power. All the lights faded out, then turned on, again and again.

Where do I start with these problems? There seems to be some serious electrical issues.
Maybe some of the codes were caused by low battery voltage. I hooked up the battery charger and will rerun the tests to see if anything changes.

04-20-2017, 09:56 PM
Im gonna guess a bad ground somewhere

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