Check engine light on
10-02-2018, 09:22 PM
#1
Member
Thread Starter
Check engine light on
Hi all, after getting the tyres done and feeling happy, as I neared my friends place where I was staying, the check engine light came on. Car driving normally with no noticeable issues. Parked the car up took the petrol cap off and put back on again. Checked the water level, topped up with about 200mls of coolant. Still on the next day when I went to leave. Called into a Mercedes repairer and he put the Star diagnostic onto the car. It bought up two stored codes, but he could not tell me if they were recent or old ones. They are P2026 Purge control valve, and P2027 Charge air temperature sensor. Temperature rise implausible, check coolant pump and additional radiator.
Can anyone shed any pearls of wisdom as to what I may need to do, check, change?
Cheers,
Graeme
Can anyone shed any pearls of wisdom as to what I may need to do, check, change?
Cheers,
Graeme
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Kiwibenz (10-02-2018)
10-03-2018, 01:22 AM
#3
Member
You said someone did a quick-test with Star diagnostics. Did they give you any printouts? Anyone who knows what they're doing should be able to tell easily which fault turned on the CEL and exactly when each fault was set (freeze frame data). You can tell which fault turned on the CEL just by looking at the print-out from the quick-test (it will have a little light-bulb icon on the right side). To see freeze frame data you simply go into the control unit (ME) and select the fault (or print the faults and it will prompt you to print freeze frame data too).
Without more info, it's kinda hard to give you a diagnostic path. You have two completely independent faults and only one of them is relevant to the current CEL. The purge valve code could be nothing or you might need a new purge valve. The intake air temp fault code could be caused by a bad intercooler pump so I would look into that first. There has been a lot of discussion on here regarding the symptoms and repair of this problem, so I'm not going to spell it out again, just search for it. In short, the original intercooler pumps on these vehicles are known to fail (a lot!). You may notice a severe lack of power after one or more wide open throttle runs. You may not notice much of anything, depending on how you drive. If it's bad or there is any doubt, replace it with a Bosch "010" pump or similar and be sure to bleed the system properly.
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Kiwibenz (10-03-2018)
10-03-2018, 04:21 PM
#5
Member
That's not Star diagnostics, but based on the "MIL: On" I see after the purge code, I'm guessing that is the code that turned on the check engine light. Perhaps someone more familiar with whatever scan tool that is can chime in and verify. Testing a purge valve is pretty easy (the valve should be normally closed, but open when applying 12V), however, the failure is probably intermittent so it may be tough to verify by testing. I would take a quick look at the wiring and hoses at the purge valve and if you don't see anything wrong, I would go ahead and replace it. I would strongly recommend to stay away from aftermarket parts. I believe the same valve is used on many MB models from that era so they should be available used on ebay if you want to save a few bucks.
Even though the charge air temp fault does not appear to be the one that turned on the CEL, I would still double check your intercooler pump because that is a very common problem. (Just because the CEL isn't on for that fault doesn't mean that it's not also relevant.)
Even though the charge air temp fault does not appear to be the one that turned on the CEL, I would still double check your intercooler pump because that is a very common problem. (Just because the CEL isn't on for that fault doesn't mean that it's not also relevant.)
