Error Codes

Does anyone know the meaning of these error codes?:

P0130 and P0150

I have a 2004 Audi A4 that won’t start and it’s coming up with these error codes.

These should be O2 sensor codes and this is not likely to have anything to do with a no-start condition.
It would be helpful to put all info into one post since your other posts mention the car dying on the freeway and a question about a “fuel pump relay switch”. There is no pump relay switch per se because a relay is a switch; it’s just operated electrically rather than with a finger.

It helps a lot if the problem can be narrowed down a bit as to whether it’s fuel, spark, or worst of all; mechanically related.
When it died on the freeway there was no brief second or two of rattle or a BRRRRR sound was there? When the engine cranks over does it sound normal or does it appear to crank over easier and faster than normal?
(Just theorizing in case a timing belt decided to let go).

After that, I would suggest spraying a healthy shot of carb cleaner into the intake and attempt to start it. If it starts and runs for a second or two then you may have a fuel pump failure. This also leads to other things such as how often the fuel filter has been changed, how many miles on the car, etc.

Code P0130 is for the O2 sensor circuit for bank 1/sensor 1. The other code is for the O2 sensor circuit for bank 2/sensor 1. These are the sensors on each side of the engine before the CATs. There is something wrong with the wire connections to the sensors. Check for bad connections to those sensors.

There is a common ground for both O2 sensors. IIRC, it’s located near the coolant tank on earlier models, not sure on the '04. Sometimes this corrodes.

You posted that your car died on the highway. '03 VW and Audi B5 platform vehicles were subject to a recall on the fuel pumps, so this likely does not apply to you. However, perform the following test:

Get a helper to sit in the driver’s seat and turn the ignition key to on (but not start) while you put your ear to the floor of the trunk. Listen for a whining sound coming from under the trunk. It should run for 2 seconds or so, and cut out. If it passes this test, then your fuel pump is fine.

If not, you’re going to have to check the voltage at the fuel pump connector. Performing the same test as above, you should get around 13V on the connector. If not, you have a failed relay or fuel pump fuse in all likelihood, or an issue with the ECU. The latter is the least likely explanation.

Thanks so much for your response. I cannot detect the sound of the fuel pump priming when I turn the key on. I disconnected the fuel line, cranked the engine (it’s cranking normally) but got no fuel at the disconnect. The fuel pump fuse is good, there’s plenty of gas and the battery is fully charged.

Thanks for responding to my post. Sorry about the “afterthought” postings.

When the car died while driving it, there was no rattle or BRRRR sound. It cranks normally.

I disconnected the fuel line, cranked the motor but, got no fuel at the “disconnect”. The battery is fully charged, fuel pump fuse is ok and there’s plenty of fuel in the tank.

I just realized that I cannot hear the fuel pump priming when I turn on the key. I will try the carb cleaner into the intake. This car has normal mileage for a 2004 (62,000) and I use only super octane gasoline. It has been routinely factory serviced by Audi dealership up to 50,000 miles.

Thanks so much for your response.

You wrote: These are the sensors on each side of the engine before the CATs.

What are CAT’s?

I do not have a wiring schmeatic handy for your car but tracking down this problem may require a diagram and a methodical approach.

Most modern cars use a system of controls for the pump as mandated by Federal law. This requires the pump to quit running when the engine quits due to a collision, etc. This prevents the pump from continuing to force high pressure gasoline through a broken fuel line onto a potential engine fire.

The usual method is that the pump receives its power through a fuel pump relay. The relay is normally activated by a ground provided by the ECM (computer). The signal that causes the ECM to provide this ground is provided by a pulse from the ignition module.
If the pump is suspect, about all I can recommend is locate the fuel pump relay, and assuming it’s a normal Bosch relay, there should be a terminal 30 and 87. These are the 2 main leads for the pump wiring. One terminal should have power at all times. If not, you have a fuse or fusible link problem. If there is power at one of those terminals try running a jumper wire from 30 to 87. Note if you hear the pump running and the car will now start.

If not, likely a bad pump. If it does start, then it’s a control issue (ign. module, ECM, etc .)
Keep in mind that over time if an electric pump is forced to operate with a partially clogged filter this will shorten the life of the pump and can even burn the contacts in the fuel pump relay.
Don’t know how much help that is but that’s about as exact as I can be without a diagram to eyeball. :slight_smile:

You’re going to need a voltmeter, or at least a test light, to do the rest. ok4450 was pretty much dead on on how to proceed. Check for voltage at the fuel pump connector (there are 4 contacts, I believe, 2 pair for the pump, 2 pair for the fuel level sender- I believe the outer 2 are the pump’s wires.)

I would recommend getting the repair manual from Bentley Publications if you want to do any diagnostic here, or you can subscribe online at and get access to the repair manual’s online version.

Also check out for loads of technical advice. You’ll get lots more specific help there if you post what your problem is.

What are CAT’s?

Catalytic Converters.

Thank you so much for all your advice! I completely forgot about the issue which mandates the pump to quit running in the event of a collision! Thank you ok4450!

I will take your advice and check out Audi World for additional technical advice and most likely purchase the repair manual from Bentley before taking the car to my Audi dealership for a $600.00 diagnstic workup!

Thank you everyone who has responded! Lots of good advice… now I just have to get this car running again!

Thank you ok4450! I think the regulation mandating that the fuel pump shut down in the event of a collision is a great clue to my problem. I was hoping it was something simple (like a fuse).

I have a friend coming over today to help me with these more technical issues and hopefully get this car running!

Thanks to everyone who has responded!