Knock Sensor Question

[Konstantin Bogach]

My 200tqa '89 had the same problem. 2142 only above sertain rpm and on bumps.  "New" knock sensor from
local junk yard cured the problem.

Konstantin Bogach.

> I've been playing with the boost in my '89 200Q.  If I go too high with the
> boost, I get a check engine light above 3800 rpm.  When I check the error
> codes, I get an error code 2142.  Investigation on SJM's sight gives the
> following explanation for the error code:
>
>     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 can drive the car forever and not get the above error code if I have stock
> boost.  My question is, if my knock sensor is bad, how come the computer
> only realizes it above stock boost levels.  The higher boost could certainly
> cause knock, but then wouldn't I get the following error code if that was
> the case:?
>
>     2141
>     Knock regulator #1
>     Excessive knock, timing is being retarded by maximum amount 7.8 degrees,
> Low boost on 20V,
>     Fuel octane too low, Excessive Compression, excessive boost
>
> If anybody can help me to understand if I have a problem with engine knock
> or just a faulty sensor I would appreciate it.
>
> TIA,
>
> Dan
>