I just got a check engine light come on. Pull the fuse box cover and found fuse number 7 blown. Replaced the fuse but still has the engine ligh come on. Check the malfunction indication code in the diagnotic box near the battery and found Code 5 (Exhaust gas recirculation inoperative) and Code 21 (Purge switchover valve, open/short circuit). Where are the exhaust gas recirculation valve and purge switchover valve. Can I fix it or do I have to bring the car to a MB mechanic. Any suggestion is appreciated.

Duc4208

Do a search on how to reset the light. If it comes on again then fix whatever those problems might be.

I've read that code 5 is usually caused by a clogged tube, try a search on that too!

Whenever in doubt, try a search

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500

I reset the DTC by pressing the switch 8 seconds after each code is read. The code is still #5 and #21 consistently. Reading the posts, I knew the location of the EGR and it is above the exaust manifold. But where is the purge switchover valve (SOV). Researched in the MB shop manual, there is a exaust gas recirculation SOVs. Is it the same as purge SOV . Authur, if you read this message, could you provide me the procedures for testing the purge SOV valve for Code 21. Does fuse #7 being blown has anything to do with Code 21 or only a bad fuse. Fuse 7 provide power to EGR SOV and purge control valve. I will test the EGR valve as Authur suggested using the vacum pump.
Thanks in advance. I have use this forum to fix the idle problem as posted in the past.

I would concentrate on the cause of the blown fuse. Possibly the wire to oxygen sensor has fused to the exaust pipe.. or a similar short in the circuits of fuse 7.

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Earl



1993 190E 2.3
2000 Toyota 4x4 Tundra

Update on the check engine light.

I think I fix the problem. When the fuse Number 7 blown due to a bad fuse not a short circuit, it created a check engine light DTCs #5 and #21 because the power supply to EGR system was interupted. I replaced the same fuse but the check engine light was not go away. When I reset the code by holding the switch for 8 seconds after reading each code, I did not turn off the key so the LED is still flashing with the same codes. Today, checking the DTC again, there is no faulty code. I test drive and no check engine light on. I did not know that I have successfully reset the code and no thing wrong with the car. The one lesson learn from this is after reset the code, turn off the key to to reset the check engine light. Thanks for giving me good advices.

You've learned how to reset the light, but that doesn't mean the problem has gone away.

I forgot the exact details, but a fault needs to occur a number of times in a specific period of time for a Check Engine light to illuminate.

A random fault that occurs just once will not set a code.

Give it a couple of weeks and then report back.


Since we have the same car, I have posted numerous times on fault codes and check engine lights, etc.

Do a search on my name.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

So far, the check engine light does not come on. I have driven the car for a week now. I think I reset the check engine light and no thing wrong with the car. The check engine light came on because of a blown fuse. After replacing the fuse and reseting the check engine light, the car is in good condition.