TheSamba.com :: View topic - 2001 Eurovan GLS

Sun Nov 23, 2025 1:37 pm

A few days ago, my check engine light came on. I did an OBD2 scan and got error code P0411 Air Injection Incorrect Upstream Flow Detected. No other error codes in any other system. The car still drove fine and I was planning on troubleshooting the aux air system. Today I went to start the car to check out the if the secondary air pump runs and the car wouldn't start. It turns over but won't catch. I did another OBD scan and there are no additional error codes. My battery is relatively new (about 7 months old). With the ignition switch off, it measures about 12.3 volts. When cranking, it drops to about 10.5 volts. There are no unusual sounds when cranking, just no-start. Any troubleshooting suggestions or ideas would be appreciated. This is my first foray into a non-air-cooled "modern" VW. Thanks.

Sun Nov 23, 2025 2:09 pm

What scan tool are you using?
Most here use the VCDS scan tool. I have tried the auto parts store scanner and found that the VCDS will detect more fault codes than the FLAPs scan tool.

Sometimes, simply disconnecting the battery for 15 minutes to half an hour will clear things up with the ECU.

Have you looked for any blown fuses, especially for the fuel pump?

Someone way smarter than I will chime in with better ideas than what I have posted today.

Welcome to EV hell!

Sun Nov 23, 2025 3:32 pm

My OBD2 scanner is an Innova 5610. I did check the fuel pump fuse and it's fine (it has continuity).

Sun Nov 23, 2025 5:38 pm

61 BUS wrote: A few days ago, my check engine light came on. I did an OBD2 scan and got error code P0411 Air Injection Incorrect Upstream Flow Detected. No other error codes in any other system. The car still drove fine and I was planning on troubleshooting the aux air system. Today I went to start the car to check out the if the secondary air pump runs and the car wouldn't start. It turns over but won't catch. I did another OBD scan and there are no additional error codes. My battery is relatively new (about 7 months old). With the ignition switch off, it measures about 12.3 volts. When cranking, it drops to about 10.5 volts. There are no unusual sounds when cranking, just no-start. Any troubleshooting suggestions or ideas would be appreciated. This is my first foray into a non-air-cooled "modern" VW. Thanks.

Start with the basics:

FUEL - pull the source line off the fuel rail and have someone turn the engine over / be careful that thing will squirt a lot if your pump is good.

SPARK - remove a spark plug wire and using a spare spark plug (I know - prob go get one) connect the spare spark plug into the wire and hold the plug threads against a good ground... Have helper crank again and watch for spark - should be a strong blue spark jumping the gap of the spark plug.

If you have both (you probably don't) look for a massive vacuum leak like the air-intake boot being ruptured or disconnected.

Message the forum back with your results.
(and yeah: welcome to Eurovans!)

Damian

Sun Nov 23, 2025 9:19 pm

Need to get a scanner to check your crank position sensor, that will cause no start, easy fix too.

Also fuel pressure if the CPS checks out.

Tue Nov 25, 2025 11:00 am

Most likely, it'll be a fuel pump. If it's a crank position sensor a generic OBDII reader will pick up a faulty one of them. It's not the immobilizer as if it was, it would run for about a second and shut off. As for the coil packs, it would be rare for them to lose power.

As for fuel, it'll never throw a code (EV is too old) and a good fuse does not mean the fuel pump gave up the ghost and ended it's life. I would guess if you could search here for where the fuel pump relay is, then jumper it. If you do that and there's total silence, then it's the culprit. If it does run you can also still open a fuel line and see if fuel comes out.

Tue Nov 25, 2025 11:29 am

Give the Air Intake at the Air Filter a shot of Starter Fluid then crank
If it starts you might have a Fuel pump problem

Tue Nov 25, 2025 1:05 pm

jjvincent wrote: Most likely, it'll be a fuel pump. If it's a crank position sensor a generic OBDII reader will pick up a faulty one of them. It's not the immobilizer as if it was, it would run for about a second and shut off. As for the coil packs, it would be rare for them to lose power.

As for fuel, it'll never throw a code (EV is too old) and a good fuse does not mean the fuel pump gave up the ghost and ended it's life. I would guess if you could search here for where the fuel pump relay is, then jumper it. If you do that and there's total silence, then it's the culprit. If it does run you can also still open a fuel line and see if fuel comes out.

A quick and dirty test for a bad fuel pump is to give the bottom of the fuel tank a few good thumps, preferably while power is applied to the pump and see if it then starts. A rubber mallet or dead blow hammer works great for this.