Accelerator pedal unresponsive more and more often - prevalent issue!

[03VW4ME]

My wife drives an 03 Jetta with the 2.0. 92k on the odometer. 5 speed transmission.

The accelerator becomes unresponsive at random times, but usually when at steady speed or during acceleration.

This is an extremely widespread problem and it can surely be only 1 or 2 issues.

What is the fix?

(FYI, this car has been babied and well-maintained. Within the last 500 miles, it has also received new spark plugs, a new coolant temp sensor (which did NOT solve the P0118 engine code), and a new crank sensor.)

[Anony00GT]

For P0118 (ECT Circuit High)...Did you replace the sensor with an OE green one? If you used an aftermarket sensor, get an OE one and retest. If you used an OE one, verify all the wires between the sensor and ECU.

Any other codes at all? What type of scan tool(s) do you have access to?

[03VW4ME]

I bought whatever was available at O'Reilly Auto. Is an OEM replacement THAT much better?

I have an Innova scanner that is being replaced because mine froze. Once I get it back, I'll connect it and monitor real-time data.

It's frustrating that I have zero codes referring to the throttle issue....
...you'd think that would be a significant enough problem to pop a CEL.



No one has found a fix for this issue?!?

[Anony00GT]

Get an OE green sensor and retest. The made-in-China parts store ones are junk. Heck, the OE one is only about 30 bucks anyway. Might want to break out the wiring diagram and properly test the circuits first though.

Before buying another Innova generic scan tool, consider VCDS, especially if you're doing a lot of work on this car yourself. It'll pay for itself quick, as will a proper service manual. Heck, you may have code(s) that the generic scanner isn't reading even, definitely seen that before.

Remove and thoroughly clean the throttle body. Re-install and do a throttle body alignment with VCDS. Then, while youve still got VCDS hooked up, run the readiness script and see where you end up with the throttle problem.

[03VW4ME]

Ok, I'll run with an OE sensor on the CTS.

On the original question, though, I think the unresponsive throttle is linked to the amount of fuel in the tank. It sounds dumb, yes , but the issue only happens when the tank is at or below 1/4 full. However, it does happen when at steady speed on a level surface. So it is not an issue of the fuel pump running 'dry' on an incline or acceleration/deceleration (I don't know if the pump is at front, rear, or center of tank).

That said, I am going to put a new fuel filter on (a good one, as I don't remember what the last one was). The existing fuel filter doesn't have many miles on it, but I'll pull it and check for flow.

I am not going to buy a VCDS, because I have 4 project Jeeps and 1 Volkswagen. And my wife now wants a Jeep.

[Anony00GT]

Problems like yours can be tough to diagnose without the proper scan tool. First things first, fix the temp sensor issue. That sensor is key in A/F control.

Then, I have two suggestions as of now:

The first will probably sound dumb to a Jeep guy: visually check the O2 sensor wiring. Shorted O2 sensor wires can cook the throttle drivers in the ECU, and generic scanners don't always pick up those fault codes. This is more commonly seen when people modify their exhaust to bigger pipes and the O2 wires burn against the pipe, but it can happen if the wires get damaged in a stock application as well. I've also seen in the past examples of this issue where a generic scanner says no faults, and then VCDS sees APP and O2 circuit codes.

and then, if the above checks out,

If your tool gives you a datastream, monitor (if all are available in generic OBDII) TPS, APP, MAF and fuel trims while driving, and while the problem is occurring.


If you don't want to buy VCDS, that's up to you. However, scanning a VW with generic OBDII can be near useless. If you want to dump the car and buy her a Jeep, do it. If you want to scan the car properly, type your zip code into this thread to find someone local who can help you out with VCDS:

http://forums.vwvortex.com/showthrea...-in-the-thread