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Discussion Starter #1 (Edited)
Hello. I am hoping you guys can help me.

I was driving home when my car stalled out at a red light. I started my car back up, drove a little, and it stalled out again . Every time it stalled out, the engine jumped and the car jolted. I was able to get it home (I wasn't far) but it did stall out one or two more times. When I got home, the car gave me 15 different error codes. They are listed below.

P0010 - A Camshaft Position Actuator Circuit / Open Bank 1
P0031 - H02S Heater Control Circuit Low Bank 1 Sensor 1
P0037 - H02S Heater Control Circuit Low Bank 1 Sensor 2
P0051 - H02S Heater Control Circuit Low Bank 2 Sensor 1
P0057 - H02S Heater Control Circuit Low Bank 2 Sensor 2
P0102 - Mass or Volume Air Flow A Circuit Low
P0134 - 02 Sensor Circuit No Activity Detected Bank 1 Sensor 1
P0141 - 02 Sensor Heater Circuit Bank 1 Sensor 2
P0154 - 02 Sensor Circuit No Activity Detected Bank 2 Sensor 1
P0161 - 02 Sensor Heater Circuit Bank 2 Sensor 2
P0414 - Secondary Air Injection System Switching Valve A Circuit Shorted
P0418 - Secondary Air Injection System Control A Circuit
P0445 - Evaporative Emission System Purge Control Valve Circuit Shorted
P2096 - Post Catalyst Fuel Trim System Too Lean Bank 1
P2401 - Evaporative Emission System Leak Detection Pump Control Circuit Low

It is a 2003 Passat Wagon GLX V6 4motion.

I don't really know what is going on. Could it be the ECM? Or wiring? Anybody have ideas?

Thank you!!
 

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Discussion Starter #2
UPDATE: It looks like the ECM Fuse was blown. I replaced it but it just blew again. Any ideas what I should check next?
 

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Which specific fuse was blown/keeps blowing? I'm guessing 34, based on the codes. Every code, except P2096, is for a device powered by Fuse 34.

The problem is likely wiring fault (mice, heat) or a failed device (solenoid, O2 sensor, etc), rather than the ECM itself. With the specific fuse number, the schematic (in the Bentley manual) will tell us exactly where to look.

Are you experienced using a multimeter? If so, you can find the problem.

The first measurement would be to check resistance from the load side of the blowing fuse to ground. Assuming Fuse 34, any green/yellow wire under the hood would be this circuit.

Another approach would be to unplug the four O2 sensors and see if the fuse holds--they and their wires are most subject to heat damage, thus the most likely culprits.

The circuit arrangement isn't necessarily what you would expect. Generally, the +12V wire goes directly to each device, unswitched (but fused). The negative wire for that device (e.g. solenoid) is switched by the ECM. The basic design reason is that a short to ground on that wire (the most likely fault) causes the device to switch on, but won't damage the ECM (because no current will flow through the ECM).

This design does make some of the fault codes tricky to interpret. I suspect all your codes (except P2096) are due to loss of power to the devices, not the devices themselves.
 

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Discussion Starter #4
Thank you so much! It is Fuse 34. I unplugged all the 02 sensors and the fuse did not blow. I then added them back one by one. After some trial and error, I determined Bank 2 Sensor 2 must be blowing the fuse. It is the 02 sensor with a brown connection. I am going to check the wire now, and then replace it if I can't find anything.

I did notice something odd. I have a ATQ engine and inside of my car it had a 15AMP fuse. In the Haynes manual I have, it lists Fuse 34 as a 20AMP fuse. The electrical diagrams they have in the manual may be out of date and I wanted to see if anyone could verify the correct amperage for that fuse.

ALSO, something else I noticed (when I originally replaced the fuse) is that my engine is pulsating when I first start it. The car almost feels like it is about to die (the headlights fade), and then the engine revs back up. After about thirty seconds to a minute, it levels out. IF I rev the engine up though, it does the same pulsating thing. Any idea what this could be? It imagine it must be related, unless it is some serendipitous thing.

Thank you again for the help!
 

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Discussion Starter #6
Okay, I cleared the codes and the pulsating idle disappeared. I should have done that right after finding the problem! I couldn't see any obvious areas where the cable would be shorting, so I am going to replace the whole thing.

Question though, from my understanding this 02 Sensor is not the most important because it is post cat. Would I be okay to drive around without replacing it? I know I need to get it done, but may hold off for a little.

Also, finding this problem saved me some money and with everything going on, that is huge.
 

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Discussion Starter #7
Also, I am just getting codes.

P0056 - H02S Heater Control Circuit Bank 2 Sensor 2
P0161 - 02 Sensor Heater Circuit Bank 2 Sensor 2

I have not driven around extensively, so there may be more, but these were the immediate ones.
 

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It is OK to drive it until you get the replacement sensor. That sensor is just for reporting pollution problems, it doesn't control anything.
 

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I did notice something odd. I have a ATQ engine and inside of my car it had a 15AMP fuse. In the Haynes manual I have, it lists Fuse 34 as a 20AMP fuse. The electrical diagrams they have in the manual may be out of date and I wanted to see if anyone could verify the correct amperage for that fuse.
Per Bentley schematic 69/13 (for the ATQ engine), Fuse 34 should be 20 amps.
 

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Discussion Starter #10
It is strange that my car had the 15 amp one. Is there any reason for me to be worried if I switched it over to a 20 amp fuse?
 

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No ;problem with fitting the correct 20A fuse, the 15A fuse was probably fitted because they didn't have the correct one.
 

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Also, I am just getting codes.

P0056 - H02S Heater Control Circuit Bank 2 Sensor 2
P0161 - 02 Sensor Heater Circuit Bank 2 Sensor 2

I have not driven around extensively, so there may be more, but these were the immediate ones.
Both of those codes indicate a problem with the rear O2 sensor on bank 2. I'd guess you would get those or something similiar if the car is operated with that sensor disconnected. If the sensor was connected the code is saying there is a problem with the heater circuit for that sensor, which is probably a short that is causing the fuse to blow.
 

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Discussion Starter #13
New problem. The car is cranking but not starting. I have worked through some of the blogs, and will continue to look, but I wanted to see if anyone knew of the issue.

Again, the car cranks fine but it will not start. It was fine one day and then just wouldn't start the next, Below is the list of checks I've performed.

1.) There is half a tank of fuel
2.) Battery is reading 12+ volts and does not dip below 11 volts during cranking
3.) The fuel pump fuse is good
4.) All the other fuses are good
5.) The fuel pump relay is good and was even replaced by a spare I had
6.) The fuel pump is getting enough voltage
7.) The fuel pump can be heard on start up whirring
8.) No visible fuel leaks
9.) I have one check engine light P0056 - H02S Heater Control Circuit Bank 2 Sensor 2 (I unplugged this sensor because it was causing my car to fail -- see above)
10.) The timing belt was replaced 2 years ago so it shouldn't be anything related to that
11.) The car is parked on a hill BUT the tank reads more than half full SO I can't imagine it is that

Anyone know what I should check next? It really sounds like the car is just struggling to get fuel. It just cranks and cranks and cranks. I did clean the MAF recently but that wouldn't cause the car not to start? Even if I damaged it.

Any ideas or thoughts? Thank you.
 

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It could very well be the engine is flooded. There are a few threads floating around about how to deal with that.
 

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Discussion Starter #15
I looked into that. I tried starting the car with my foot to the floor (to try and evaporate the gas) but it did not work. I even took out the fuel pump fuse and tried cranking it that way. I do not believe the engine is flooded.
 
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