1995 E320 Engine Light Codes 4,5,6 & 26
 

Hi I am new to the forum and recently obtained a 1995 E320 from my parents. I am not sure of the past few years history on the car but it has 191k in miles. The car has been having a hard time going into reverse which I have been told that typically that results in a transmission rebuild. My bigger problem is the engine light with codes 4, 5 and 6. When the engine is cold, it runs rough and then it can stall at times. Once it is up an running warm it runs smooth. If I give it a lot of gas it may sputter a bit but then smooths out. Any ideas on what it may need would be great. I have read a few postings that suggest a new wire harness may be needed but before I go to that extreme, I thought I would post and see if anyone has other ideas. Thanks for any help you can provide.

The way I read it, you have at least three separate issues in front of you:

- Sluggish reverse. I'm working from memory, but this may be solved with a repair, not a rebuild. Search "B2 piston".

- Codes 4, 5, and 6.

Code 4 - "Air injection system faulty hot film mass air flow sensor with hot wire"
Code 5 - "Exhaust gas recirculation faulty"
Code 6 - "Idle speed control faulty"

Codes 4 and 6 may be from a flaky engine wiring harness. It should be replaced. Some mechanics won't even begin to diagnose driveability issues unless the original engine wiring harness has been replaced on these models.

Code 5 is a blocked EGR tube that needs to be cleaned out.

- Code 26 - "Upshift delay faulty"

The upshift delay valve likely developed a leak.

A lot has been written on these issues. Rather than myself typing out all the fixes, please search using keywords "blocked EGR tube", "Code 5", "Code 26", "upshift delay valve".

1995 E320 Continuing error codes 5, 6 and 26
 

I originally had codes 4,5,6,10 and 26. I am down to 5 and 6 right now. Thank you for your response Kestas. At this point I am mainly focused on the codes 5 and 6. I understand the code 26 is an issue with a upshift delay module or vac issue that is intended to heat up the cats at start up on a cold engine. I have found some work arounds on that and will see if it keeps the code from reappearing.

For my other issues, so far, I have replaced some vac lines associated with the EGR valve and the air pump. I have replaced the EGR valve itself as well as cleaning the tube that goes around the engine.

After cleaning the tube a few months ago, I cleared the codes I had at that time and they all appeared again within 20 miles and a few cycles of the engine. Also at that time I had replaced one or two vac lines that I found that were either broken or had fallen off and were hanging down from the air pump.

Now I have replaced the EGR valve and the vac line off of it.

I am wondering if there are other vac lines that would affect these issues as the ones I have replaced so far have been very brittle for the clear plastic type or dry rotted for the rubber types.

I have a new O2 sensor that I purchased to install as I am sure it needs it badly since it has 196k on the engine. I also looked at all the wiring in the engine bay and it does not look like it is bad at this point.

Any pointers would be great.

Im back. The car in question has been sitting for a while. I have now replaced the upper engine wire harness, new battery and the transmission has been replaced.


The engine runs rough and idles very low. Shows codes 6 and 7 now. Idle Speed Control inoperative, and Ignition System Failure. Any thoughts?