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Re: Fault code 2 1 4 2, knock sensor

In message <199907150311.XAA28580@euler.adams.com> Gisli Ottarsson writes:

> I am now getting fault code 2 1 4 2.  Mockry writes:
> 2142
>          Knock sensor #1
>          Open or short circuit, Defective sensor
>          Check sensor and wiring
>          Symptom: Timing retarded, High fuel consumption, power loss,
>          Boost pressure not attained
> I am at a slight loss how to debug this, short of sticking in a $100+
> replacement.  How the heck do I check the sensor?  Is there a simple
> check for open or short circuit that I can perform with a multimeter?

We call this the "find a friend" code.  We just get two cars and swap
'em over.  Torque is _CRITICAL_ to proper knock sensor operation - it
has to be _exactly_ 20Nm.  I have a TengTools torque wrench from 5Nm to
25Nm that I keep from precision stuff like metering heads, and I use
that and a 15mm Stahlwille Crowfoot socket to tighten knock sensors.

Even then, taking them out and putting them back in can occasionally
solve problems.  The knock sensor is the closest the MAC1x series of
ECUs comes to the bleeding edge of technology.

Also check the contacts in the carrier at the rear of the engine bay.
Note that a 'green' knock sensor cable shouldn't be plugged in to a
'red' socket unless the pins in the socket are replaced with gold
plated ones.

 Phil Payne
 UK Audi quattro Owners Club
 Phone: 0385 302803   Fax: 0870 0883933