Check engine light, codes 8 and 26 - Mercedes-Benz Forum

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post #1 of 3 (permalink) Old 03-08-2004, 10:43 AM Thread Starter
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Check engine light, codes 8 and 26

Code 8 is the coolant temp sensor, open or short circuit, where can I find this sensor on the 94 E320 Wagon. The other is a mystery, number 26 Upshift Delay Switchover Valve - open or short circuit. Can anyone shed some light on this one? The Check Engine light came on the other day and has stayed on since. I tried to reset it by disconnecting the negative on the battery for 15 seconds, but light still stays on.

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post #2 of 3 (permalink) Old 03-08-2004, 11:04 AM
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RE: Check engine light, codes 8 and 26

Whenever I have heard of disconecting the battery, I have seen periods like 10 mins, not 15 seconds.

London, right in the middle
03 CL500 (Black/Grey, 48k, Comand, 7GTronic, Keyless Go) 302 Bhp
01 E430 (Silver/Black, 112k, Comand, Lingua, 7 seats, tow...) 275 Bhp
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03 A210 AMG (Black/Black, 63k, project rescue car) 140 Bhp

...I make that 917 Bhp...!
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post #3 of 3 (permalink) Old 05-01-2004, 12:57 AM
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RE: Check engine light, codes 8 and 26

Code 26 is Upshift Delay Switchover Valve. This is kind of annoying one to fix. The part itself is a solenoid vacuum switch that can be bought on Benzbin for $28.

It is located behind the break booster cylinder in 104 engines.

The odd part, however, is that the switch itself does not go bad very often. Probably the problem is in leaking vacuum tubes either one that come in, or the one that leaves out. They need to be tested first using hand vacuum pump. They should keep pressure of 15 bars for 30 minutes.

If there is a leak, replace tubes first. Only as a last resort, replace the valve itself.

They quoted $250 to fix it all at the dealer.

The function of this valve is to delay upshift of the transmission when the engine is cold. This is done purely for emission control purposes. It cannot hurt engine.

Again, the only annoying thing about it is the "check engine" light.

Speaking of which, do not disconnect battery to reset codes. Here is the procedure to reset them:

Read all codes first.
After the first code is read again during the second go around, wait for 3 seconds and press the button for 10 seconds.
Repeat the last step for each code.
Turn-off and turn-on ignition.

Hope this helps.
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