OBD II drive cycle to reset monitor flags - PeachParts Mercedes-Benz Forum

#1 02-23-2003, 03:03 PM

I am working on a 1996 280C. After replacing the fuel control computer and getting version coding Ineed it to pass inspection. Three of the OBD II monitor flags still show "not ready" on the scanner after three days of driving every drive cycle that I know to work on other makes of vehicles. The CATALYST, SECONDARY AIR, and EGR monitors are still left to set, I hope somebody can help me out and tell me the drive cycle procedure for any or all monitor resets on the mercedes. Thank you if you can ,CARL P.

stevebfl · #2 02-23-2003, 05:50 PM

I'm pretty sure there is no exact drive cycle that will get them all. Some monitors only run after conditions are met and its possible to never meet them. The evap monitor is usually the last and if the tank were kept full or empty it would never run.

MB says that it can take a thirty minute test drive to set all monitors. I have driven cars for days without the evap monitor running. Hopefully someone has a magic bullet.

mbdoc · #3 02-24-2003, 08:06 AM

The catayst monitor takes about 2 weeks to past readiness test.
The EGR should perform test durning de-cel every time that you drive UNLESS you are a 2 footed driver. You need to COAST downhill for 4-5 seconds with the engine at 1800-2000 RPM for the EGR test.
Also the secondary air-injection test needs about 10-15 minutes of driving & then setting at idle for 1-2 minutes.

#4 02-24-2003, 08:42 AM

Ready for this?

Begin with a clod engine, or a COLD engine.

1. Idle 20 secs.Acel gradually and drive at 20-25 mph for 1 min. vary speed.
2. Drive at 25-31 mph for 35 secs. Decel to 0mph in 10 secs. Idle 40 secs.
3. Acel moderately. Drive at 20-25 mph for 20 secs. Increase speed to 40-55 for 85 secs. then decel to 0mph in 50 secs. Idle 15 secs.
4. Acel to 36 mph in 35 secs. Decel to 0 in 15 secs. Idle 10 ssecs.
5. Acel to 30 mph and decel to 0 over a 25 sec. period. Idle 20 secs.
6. Acel to 36 in 20 secs. Drive at 35 for 20 secs. Decel to 0 in 15 secs. Idle 5 secs.
7. Acel to 26mph and decel to 0 in 40 seecs. Idle 15 secs.
8. Acel to 27 in 40 seecs. Decel to 0 in 8 secs. Idle 25 secs.
9. Acel to 26 and decel to 0 in 35 secs. idle 15 secs.
10. Drive in stop and go traffic for 1 min. Reaching 25-30 mph 2 times, with no complete stops.
11. Drive at 20-30 for 2 min. and stop. Vary speed. Drive at 20-28 mph for 2 1/2 min. at varying speeds. Stop. Idle for 30 secs.
12. Acel to 28 and back to 0 in 50 secs. Acel to 20 in 10 seces. drive at 20-27 mph for 20 secs. and decel to 0 in 10 secs. Idle 15 secs.
13. Acel to 23 and back to 0 in 20 secs. Idle 10 secs. Accell to 22 mph and back to 0 in 45 secs. Idle 10 secs.
14. Acel to 25 in 30 secs. Drive at 23-28 mph for 25 secs. Decel to 0 on less than 10 secs.
15. Idle 25 scs. Acel to 22 mph and back to 0 in 30 secs.

Do this 2 times, oh the joy!

This is the Highway drive cycle , it should set all monitors to "READY" If it does not, there is a 15 step city drive cycle that I can post.

#5 03-03-2003, 05:34 AM

Quote:

Originally posted by inspector1

This is the Highway drive cycle , it should set all monitors to "READY" If it does not, there is a 15 step city drive cycle that I can post. [/B]

I thank you for your response. Not having any luck with the highway cycle, if you could please post the city drive cycle I would like to try it out before I put too many miles on this car. Thanx.

cupertino · #6 04-12-2006, 06:55 PM

Hi Carl,

Can you please post the city driving cycle process. I have a 1996 C280, It is giving me so much head ach on smog check. I have passed emission & visual, except functional.
on the OBDII Manual Mode Screen, the Catalyst, Oxygen sensor & EGR system are not complete.
so it failed the functional test.

Dealer tells me to drive 100 miles continously to do smog check while its hot.
I dont have 2 hours to drive continously..

Can someone please shed some light on it.

Thank you.

mbdoc · #7 04-13-2006, 08:18 AM

IF the front O2 sensor is even a little weak that car might NEVER perform complete READINESS! also light footed low speed driving is required!

You need 5-8 miles below 30MPH & 10-12 miles between 50-55. WITH the A/C off!

cupertino · #8 04-14-2006, 03:59 PM

How do I know if the O2 sensor is weak ?
will traffice light & stop sign effect the result ?

Thank you
Alan

mbdoc · #9 04-14-2006, 05:10 PM

Replace it & try a drive cycle again!

cupertino · #10 04-15-2006, 01:14 AM

went back to dealer today. told them that I will not be able to do the drive cycle without getting a traffice ticket. so the service manager told me to make an appointment with referee and go from there. I passed all emission part except the functional part.

#11 04-15-2006, 03:16 AM

Quote:

Originally Posted by cupertino

went back to dealer today. told them that I will not be able to do the drive cycle without getting a traffice ticket. so the service manager told me to make an appointment with referee and go from there. I passed all emission part except the functional part.

if you are going to the dealer, ask them to Reset the DM, i have had a few 1996 and newer models that no matter how much we drove them the readiness would not pass until we reset the dm. when using the factory tool there is a rest option. i am not reffering to rest the codes, but a unit reset, hopefully they will see what i am talking about in the selection menu under the dm control module. after the reset you will still need to do the drive cycle, but it should go much easier. are you near san diego?

nvilocity · #12 05-25-2015, 11:03 PM

Quote:

Originally Posted by mbdoc

Replace it & try a drive cycle again!

Dear sir
In reference to the o2 sensor being weak. I can see readings of o2 voltage and fluctuations. Is there a particular pattern or sign that its weak. Without replacing it. I'm in that smog check paradox and mayhem. All my sensors cleared and passed at the 90 mile mark. Except evap and secondary air. Filled tank bellow full evap cleared at about 120. Now at325 miles secondary will not clear. I have tested power and function on cold start and blows air like a dam hair dryer ,works fine . also cleaned out carbon deposits replaced hoses.
Now what? Do you suggest

2000 e320 300k mi..

Stevester 500E · #13 03-05-2016, 11:17 PM

Looking for smog repair mechanic in San Diego who knows 1996 Mercedes C280s well.
I had the same/similar issues in this thread.
I drove the cycle above several times. Also drove another recommended cycle several times. In total, I have driven the car over 600 miles. Many of the miles were driven attempting the drive cycles.

Two monitors will not reset, the air pump and the catalyst monitor. The smog tech said there might be an exhaust leak somewhere.

Any referrals are welcome.

97 SL320 · #14 03-06-2016, 08:05 AM

At least on the 97 model year, air pump function is tested by turning it on and watching for front O2 sensor voltage to drop. On my C280 and SL320 it is done at the first stop / idle after the engine is warmed up. ( You must sit idle for about 5 seconds. )

Cat mon looks at the rear O2 sensor. There are some capacitor / resistor foolers for weak cats that sort of work but you must move values around. The resistor lowers O2 signal voltage and the cap smooths the signal out.

Stevester 500E · #15 03-06-2016, 02:27 PM

My car passes the emission part of the smog test.
Recently, the front O2 sensor was replaced.
Should I change the rear 02 sensor?

Any good smog mechanics in San Diego?
Thanks