K, I have a stumper. Got codes 0705 (EVAP system fault or leak) and 0903 (EVAP Canister Vent Control).

First off, yes, I tried countless times to clean my gas cap and make sure it is sitting properly. I also located the Vent Control Valve and the electrical connector seems to be in good shape. As far as I can tell, all hoses under the car seem in good order and I don't smell and fumes or vapor anywhere.

Whats weird, is I had been working on a knock sensor problem and a MAP/BARO solenoid problem, which I fixed. This EVAP problem didn't appear until after I fixed everything else and I got gas that afternoon. The ECU FAQ says the MAP/BARO valve can be a source of the code 0705 problem. But everything looks in order.

any ideas? Its a '96 GLE. Thanks all. By the way, can anyone tell me exactly WHAT the vent control valve does and how it works (yes, I already read the ECU troublecode FAQ)? Thanks.

Mike

 

anybody?????

 

Call up your local dealership and ask about a recall on 96's. I had those codes come up for no reason a while ago. I took it to the dealership and asked about a recall. They took my vin number and I qualified for the recall. They have to replace my evap box(the black box infront of my drivers side rear wheel and all my o2 sensors.

 

I had the 0903 code. I took the valve out and cleaned it + worked it back and forth while dousing it in carb cleaner.

Worked for a couple more weeks and then it came back.

I replaced the valve and canister for like 70 bucks through Courtesy. Takes about ten minutes.

I would try cleaning etc first. If anything, if it goes away for a few days and comes back then it is almost definitely the valve - might as well replace the charcoal canister while you're at it.

 

The vent control valve vents fuel vapor from the charcoal canister into the intake manifold when at higher speeds so that it can empty the canister and burn the fuel

 

I thought that was the purge valve that did that. At any rate there are two different valves, one send fumes to the intake manifold. I can't figure out why there would be another valve. It looks like the hose from this vent valve goes from the charcoal can to a much smaller black cylender, which then dumps overboard. I may be wrong, its been a few days since I've been under the car.

Thanks for the recall info. I'll check out the dealerships tomorrow.

Mike

 

My bad your right that is the purge valve the vent valve vents are through the activated charcoal and into the air

 

0705
Diagnostic Trouble Code 0705 points to a problem with the Evaporative Emission Control System.

This malfunction is detected when the EVAP control system has a leak or the EVAP control system does not operate properly. (EVAP = EVAPorative emissions.)
Possible causes include...
- incorrect fuel tank vacuum relief valve
- incorrect fuel filler cap
- fuel filler cap vent remains open or fails to close
- foreign matter caught in fuel filler cap
- a leak in the line between the intake manifold and the
EVAP Canister Vacuum Control Valve
- foreign matter caught in the EVAP CVCV
- leaks in the EVAP canister or fuel tank
- leaks in the EVAP purge line (pipe and rubber tube)
- EVAP purge line rubber tube bent
- blocked or bent rubber tube to EVAP control system pressure sensor
- loose or disconnected rubber tube
- EVAP CVCV and circuit
- EVAP Canister Purge Volume Control Solenoid Valve and circuit
- absolute pressure sensor
- tank fuel temperature sensor
- MAP/BARO switch solenoid valve and circuit
- blocked or bent rubber tube to MAP/BARO switch solenoid valve
- O-ring of EVAP CVCV is missing or damaged
- water separator
- EVAP canister saturated with water
- EVAP control system pressure sensor
- refueling EVAP vapor cut valve
- ORVR system leaks


This is a "jackpot" DTC. It points to so many things you don't know what to check. It is often combined with another DTC which is more specific and therefore more helpful.



0903
Diagnostic Trouble Code 0903 indicates a problem with the Evaporative Emission (EVAP) Canister Vent Control Valve or its associated electric circuit.

This part is used by the Engine Control Module to perform the fuel system leak test. Since it is used only for self-diagnosis your engine will run perfectly well despite the dashboard Malfunction Indicator Lamp.

The EVAP canister and this valve are located under the car, near the rear left tire. You might check to make sure all the electrical connectors in that area are secure.

There's no telling how expensive the repair will be, because no definite diagnosis has been made. Maybe you just have to re-plug a loose connector. Since the EVAP system is part of the emissions control system you might have warranty coverage.


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