Throttle position sensor problem
Richard van der Hoff
quattro at rvanderhoff.org.uk
Sun Oct 26 08:01:23 PDT 2008
Hi guys,
I've been having a bit of trouble with my 1999 S4 biturbo, and was
wondering if anyone had any experience with similar problems.
The symptoms started with an intermittent engine fault light. I plugged
in the VAG-COM and the problem seemed to be
"17581 - Angle Sensor 2 for Throttle Actuator (G188) Signal too High
P1173 - 35-10 - - - Intermittent".
Now, I've monitored the offending sensor in VAG-COM, and it appears to
move nicely up and down with the gas pedal. I've also checked for loose
or corroded connections between the sensor and the ECU, and taken apart
the sensor and checked for damage inside. All came up blank.
So I put it all back together, thinking "it'll either fix itself, or
become worse until it's obvious what the problem is".
So yesterday it got worse (on the way to a friend's wedding, of
course...) - and I lost pretty much all power; basically the engine shut
itself down to a fast idle. Fortunately after a restart it ran fine again.
I limped it back home today - the problem seems to be getting more
regular, and have pulled the codes again. I now have, in addition to the
original fault:
17950 - Angle Sensor 1 for Throttle Actuator (G187): Implausible Signal
P1542 - 35-10 - - - Intermittent
17965 - Charge Pressure Control: Positive Deviation
P1557 - 35-00 - -
So presumably both throttle sensors are out of spec at once and the
engine is shutting itself down to a safe state. I'm hoping P1557 is a
symptom of the other problems, otherwise it looks like I have a boost
leak to add to my woes.
In short, does anyone have any experience with throttle-sensor problems,
any joy in fixing it, and if (as I suspect) I need a new throttle
sensor, is it possible to obtain one without the entire throttle body?
Thanks
Richard
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