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Old 12-08-2003, 01:00 PM
joelpdavis joelpdavis is offline
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Join Date: Nov 2000
Location: Alameda, CA
Posts: 45
W140 Clear scan codes FAILED

Can someone shed some light on this problem:

Last week I took my car (here in CA) to have it smog-checked and the check engine light was on requiring the station to clear the codes prior to running the test.
As such, they hooked up their CS2000 and pulled up a variety of codes that was causing the check engine light to come on. They found one source of the problem: the air hose on the air pump was half off it's mount. They corrected it, cleared the codes and restarted the vehicle.
The check engine light was still on and when they checked the scan tool for 'current codes', it still showed five or six live codes.
They cleared it severl more times, but the same thing kept re-appearing.

I decided to tackle this another day and went to work. 4 hours later I hopped in the car and the check engine light was OFF.

SO... I now run to the smog place and try to re-check. (Saving you the lengthy detail in the middle) After many attempts the car would not pass smog on the NEW (as of Oct 1) Smog test equipment requiring a Dyno test because the ASR senses the front wheels not moving while the rear ones are.... And that causes the car to go into Limp Home Mode.

1. Why did the codes magically disappear?
2. Any ideas on how to trick the car into allowing a dyno test?

Many thanks here in CA.

Joel P. Davis
1992 500SEL
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