Can CEL and error codes be cleared without repair?
 

Hi all,

I am looking at another Benz 1996 E320 as replacement for my wrecked 1989 300CE.
When test driving I saw that CEL is on; The dealer said they will take care of it.

My concern is whether CEL and error codes can be cleared without the dealer repairing anything and I still got the problems afterwards.

Thanks!

1. You can clear codes and, depending on the nature of the problem, they could pop up again, anywhere from instantly to 5 minutes, to days.
When you look at the car, turn the key to the " ON " position & make sure you see the CEL coming on.
This will ensure that you don't have a " malfunctioning " bulb.
Shady caracters would try this trick. ;)

When the CEL pops up again days after then it would be already too late if I bought the car, right? :mad:

Is there anything I can do to avoid that?

Yes.
Get a statement in writing, saying if the CEL light comes on within the first 30 days, they will resolve the cause at their expense. ;)

Thanks manny, yes I'll try to have it in writing. But technically what can I do else? connect a OBD II scanner to see if there is any code left?


http://i245.photobucket.com/albums/g...1263_small.jpg

If somebody clears the codes & you check immediately afterward with a scan tool, chances are you would not see anything, i.e. codes present or pending.
Aside from that, you could take the car on another test-drive and, before returning to the dealer, check for pending codes.
Is this a M-B dealer you're dealing with ?

No MB-dealer, a used-car dealer in Fort Worth.
I don't think that MB-dealers have such old cars :), even if they took them as trade-in they would dump them to small dealers.

That's true.
Last time they did'nt even want my 6 year old car on their lot.
Just follow all the steps I mentioned above, before you sign on the dotted line. ;)

When I go car shopping, I carry my OBD2 scanner with me, and if I'm interested, I plug it in and check for codes as well as the system status for emmissions and such. I also make a deal out of writing down the VIN to run a car fax. I had one used car dealer that wouldn't let me use the scanner, and I walked away, the scanner will tell you if the CEL has a "malfunction".

Do you happen to know if 1996 E320 (W210) is OBD II compliant? if yes which one of the protocols ISO-9141, ISO-14230(KWP2000), J1850 VPM and J1850 PWM it has?

Thanks for your input!

Used car dealers are the lowest form of life on earth. Never trust them.
There are plenty of those cars around, so why buy one with problems from the start?

It seems like a good deal but you make me reconsider the whole thing :D

Yes, OBDII was required as of 1/1/96, which effectively was all 96 models. More info on OBDII. http://www.obdii.com/

The second section tells how to tell which communications protocol.

Just reconsider that particular car. The CEL issue can be something innocuous, and ignorable, or something serious that could have you paying for the car all over again in repairs.

I am tempted to say if the dealership was sincere, they would already have fixed the problem. However, since they don't know whether they will sell the car, they won't invest in repairs. But from what you wrote, it sounds like they will not repair anything, just reset the codes.

I recommend finding a good tech who knows the car and can give you an honest opinion. If he/she says the CEL is a minor issue, then go ahead with it. Otheriwse, there are many more to choose from.

Thanks Deanyel. The web site http://www.obdii.com/ has only instructions on how to test for GM and Ford vehicles. Do the same test procedures apply to MB cars?

General Motors Driving Cycle

A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

• <LI type=disc>Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
  
• Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
  
• Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
  
• Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
  
• Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
  
• Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
  
• Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
  
• Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

The section code intepretation also addresses only US cars.