View Full Version : Trouble shooting VW NB 2002 2.0L AVH Auto 109,000

2011.07.03, 18:58 PM
The car died and it threw some error codes. The car runs nice when operated under normal conditions, but when the outside temp is over 100 degrees with stop and go traffic it dies. Car would not restart immediately but when the car sits for 30 minutes it restarted. The EPC and check engine light came on. After idling for 1 minute I started driving when the ECP light went off. The error codes are;

P0725 Engine speed input circuit
P0135 O2 Heater Circuit Bank 1 Sensor 1
P0321 Ignition/ Distributor Engine Speed input Circuit.

My question is do you think there are multiple issues or one root problem that is causing a cascade of error codes.

It seems that if the engine has a bad Engine speed sensor, the issue would be a shifting issue. The Ignition/Distributer, Is simple a sensor to time the cam with the spark and a coil if I understand the engine. Do you think a bad cam sensor would cause the engine to die and then restart when rested for 30 min. And I hope that the O2 sensor was a random error code.

Plan of attack is to check speed sensor(P0725) resistance using this thread as a reference.

As a side note I have had my hands in the engine lately changing plugs, timing belt, thermostat, water pump, and aux radiator fan. I have double chacked the connections and they are secure.

Please comment on my plan of attack and offer suggestions.

Rabbit 16v
2011.07.04, 14:35 PM
The power for all of those things are on the same circuit. I would check relay 109 under the little plastic box in the engine compartment. If you could use your scan tool to check for rpms in measuring blocks when the car will not start, that would be helpful. Also check engine coolant temp with scan tool when car will not start. post back with some numbers ;)

2011.07.04, 21:28 PM
I did go for a drive to record some scan tool data, unfortunately the car did not die. But I think it shows that my O2 sensor on B1 S1(the side throwing a error code) is bouncing around over a range of numbers. Also the STFT B1 S2 is reading NA, what does that mean. while I was driving the outside tamp was around105 degrees.
Here is what I have;

Speed 0 47
Calc Load 6.6 23
ECT(deg. F) 201 199 Engine Coolant Temp.
STFT B1 2.3 -0.7 to2.3 Short term fuel trim bank
LTFT 7.0 7.8 Long term fuel trim bank
RPM 778 2250
IAT(Deg. F) 118 125 Intake air temp.
MAF 0.560 2.21
TPS(%) 3.5 11.3 Absolute throttle position
O2 B1 S2 0.56 0.575
O2 B1 S1 -0.031 to 0.2 -0.62
EQ ratio 1.006 to 0.99 0.989

Rabbit 16v
2011.07.04, 21:43 PM
Thats a whole lot of outside air temps! Not something I usually see in this environment ;) Its possible that the B1S1 could play a factor in your problem, but I doubt it. It doesnt help much though that the dying problem was not replicated. Perhaps try unplugging b1S1 and see if the problem persists. Terribly hard to diag a car over the internet when it has an intermittent problem. At least unplugging b1s1 will eliminate that...

2011.07.05, 01:00 AM
Yes it is very hot in Fresno this time of year, highs in the low 100's and chilly temps at night of 75.:( But in Seattle the other extreme has occurred, six sunny days in six months time, that will grow moss on your chin. Actually I miss the Seattle area very much. weather it is hiking Mt Si, or tromping though the skagit flats looking for the snowy geese. Those days were the days I know my head was screwed on straight. Good days. :thumbup: Enjoy your emerald city, the grass is not greener down south.


2011.07.05, 19:51 PM
it's been 75 - 80+ most of the last week or so :)

2011.08.02, 08:38 AM
Ok I have a resolution to my car dyeing issue. I ran out of time so I took it into the shop. They checked the resistance of the engine rpm sensor, and the cam sensor when the engine was cold. Then they ran the engine until fully warmed up then checked the resistance again. The engine cam sensor increased up to 1.2 ohms (1200 mohms). This ohm reading is out of spec and they replaced the sensor. The O2 sensor showed an open circuit which indicates a faulty O2 sensor, they replaced that also. I really don’t understand the “open circuit” condition, but I haven’t read up on the topic.
Since the repair the car was driven from California to Florida and has been happy for the last three weeks.

Take care and thanks to everybody that helped. :)

2011.08.02, 16:21 PM
thanks for posting the resolution :thumbup:

Rabbit 16v
2011.08.02, 18:15 PM
I concur! :thumbup: :beer: best thing ever!