Code P1400?
 

Hello all,

1999 ML430, 217,436 miles. Check engine light came on the other day. Scanner came up with code P1400. After investigation I found that this means electrical malfunction of the EGR Transducer, which it seems is attached to EGR valve. Changed EGR valve once 4 years ago.

My question is:

1. What could have caused this and will just switching out EGR Valve solve problem?


Thanks for any help.

That code suggests that the switch-over valve is NOT drawing the correct amount of current from the ECU.

100% electrical issue; wiring, switch over valve, or ECU.

Do you still have the old EGR valve to try the switch-over valve?

Thanks DOC but no, I don't. That was my first thought but I could not find it, so I must've thrown it out.

Anything else I can do besides purchase a new one and "test" it? Will buy from dealer as the only difference between my nearest dealer and online prices is shipping cost.

Update!
 

Finally switched out the entire EGR valve with a new one and cleaned the EGR tube while I was back there. One week now and no more CEL/P1400!

New problem though since I switched out the valve, I have been getting CEL and P0170 and P0173. I sprayed the MAF sensor with cleaner but the codes keep popping up. Could I have damamged the MAF sensor or its wiring when switching out the EGR valve?

Could be a air leak around the air intake boot where the air mass connects.

Or just a bad air mass sensor.

Take a close look at the vent hoses near the right side valve cover. They're easily damaged when they're old. You may have bumped into it when you replaced the EGR valve.

Update...
 

Checked my repair two weekends ago. I'm not sure if I was in a hurry or just tired when I swtiched out that EGR valve but I hadn't properly connected the boot to the throttle body PLUS, I left the screws on the EGR tube extremely loose. So much so that I could actually slide it back and forth some!

I straightened everything out and have not had a CEL since.

When I think back now, I was pressed for time/distracted and had to get to my sons school in an emergency. Thank goodness my screwup didn't have any serious consequences.