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2002 R230 with 54K on the clock. It has been about a month since I drove the car. Took it out and stretched its legs on the interstate for a 10 mile run. On the way back it was town driving. While at a red light the DIC showed red with "Check Fuel Cap" and the fuel light was flashing. When I got home I checked the cap and it was fine. I put a bit of lube on the rubber gasket as well. Drove the car again and all was good no lights. A few hours later drove the car again and while stopped at idle the "Check Fuel Cap" came on again and now it has the "CEL" on.
Using Icarsoft reader I checked DTC and got "P2013-000 The fault code is not in the database" further check of the ECM while running to get values showed nothing of concern. I am still getting the "CEL" on. Any ideas on what's going on?
Probably some kind of leak in the evaporative emissions control system.
Typical operation of these systems - Fuel tank vapors are not vented to the atmosphere, the fuel system is sealed, with a vent tube connected to a vapor collection cannister (usually filled with charcoal). Under certain engine conditions, a valve is opened and the stored fuel vapors are sucked into the engine. There is a sensor in the system that expects to see a minimum level of vacuum when that valve opens as the engine sucks against the closed fuel tank ventilation circuit. If this level of vacuum is not met, it indicates a leak and the system assumes the most likely point of failure, which is a loose gas cap. But it could be a vacuum leak anywhere in the system.
P2013 is a major evap system leak. US emissions regulations require a self test of the evap system. I believe that this is done by closing the vent valve on the canister and then pulling vacuum on the system via the purge valve. You need to hold vacuum for a certain period of time as measured by a pressure sensor in the tank. In order to pass this test, you need a good seal at the gas cap, good vent line from the tank to the evap canister, good canister vent valve, good purge valve, airtight purge tank, and a good purge line. This used to just throw a code and set the CEL, but because 99% of the problems are loose gas caps, it now gives you the 'check gas cap' message to avoid unnecessary dealer trips. Generally the valves and sensor would throw codes on their own, so I would suspect a cracked line. I would plug the purge line at the canister and see if you can pull and hold vacuum at the purge valve. DAS has a couple of good diagnostic actuations, but since it is US only, a lot of aftermarket tools don't have those options.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
This goes with the pdf instructions above. If you are going the keep this car and do your own work, I strongly recommend getting a copy of XENTRY/DAS even if you only use it in simulation mode without the C4 multiplexer.
12-04-2023, 10:39 AM
