Code 335 EGR Valve Voltage High

[terrinorton]

I have a 1995 Explorer. Recently the Check Engine Light came on. I took it to my mechanic. He replaced the parts he said were needed, but Code 335 still keeps coming up. So he removed the parts as it didn't repair the problem and I'm now driving with the Check Engine Light on. Can anyone help with this problem? Thanks, Terri

 

[MrShorty]

My code list indicates that a 335 has to be a KOEO code, can I assume that it is? What did he replace that didn't fix it? Because KOEO codes are set while the engine is off, they are almost always electrical in nature. In this case, it refers specifically to the DPFE sensor (aka EGR position sensor or similar) circuit. I would check the wiring between the DPFE sensor and the PCM. If the wiring is intact, then I'd replace the DPFE sensor, as they seem to have a relatively high rate of failure.

 

[terrinorton]

Hi Mr Shorty, Per my mechanics paper work, it looks like he tried to replace the egr silinoid, is this the same thing as the DPFE Sensor? Thanks for your help, I very much appreciate it! Sincerely, Terri Norton

 

[MrShorty]

No the EVR (EGR Vacuum Regulator) solenoid is used to control how much vacuum is applied to the EGR valve. The DPFE (Differential Pressure Feedback EGR) sensor measures the pressure drop across the EGR valve. Basically, the DPFE sensor is the input sensor for a feedback loop and the EVR solenoid is the output solenoid for said feedback loop.

Because a KOEO code is set with the engine off, there's no vacuum and no feedback loop operating, so the EVR solenoid wouldn't have anything to do with a KOEO 335. A KOEO 335 indicates that there is a fault "engine-off-baseline signal" (if that makes sense) from the DPFE sensor.

 

[mrmotor]

i have a code 335 also. where is the DPFE sencor located.What does DPFE stand for

 

[dpetree]

code 335

My truck is '94 XLT Explorer with CEL lit up today, so I used my scan tool to perform a KOEO test which returned the 335 code.

I previously had some issues with poor gas mileage and a miss/rough idle (when warmed up) about 5 months ago, with codes 332 and 543. The gas mileage was due to a worn fuel pump (543) and the 332 may have been related to the DPFE I thought at the time (which I also thought could have been related to the rough idle after being warmed up). I had a mechanic replace the fuel pump, sending unit and a fuse for them, and I also replaced the DPFE sensor myself, including new dealership hoses on the DPFE because they looked really bad (and I think one of them was cracked). Both codes were gone after these repairs.

SO...today I get the new code, 335 with 111, and the DPFE sensor probably hasn't gone bad again. I have literally put about 1,000 miles (maybe) on it since replacing the DPFE sensor and fuel pump, and of course clearing codes afterward. The wiring and hoses seem to be just fine going to the DPFE (as they were just replaced). I guess it is possible this new sensor has gone bad, but that doesn't seem likely.

Is there any way that some other sensor / control valve / solenoid has gone bad? I was looking at other parts that have EGR in their name and was wondering if it would be worth replacing them, or would they throw their own unique codes?
- EGR control solenoid, EGR valve position sensor, EGR valve.

I am wondering if this code and the rough idle could be related, but maybe not. My dad (who I bought the truck from) calls it a miss, and to me it just seems to run a little rough everytime it gets started after being warmed up.

What is the life expectancy of those 3 other parts I mentioned, would it be worth the $100 to replace them to ensure no more breakdowns on my 141k mile vehicle? I have had a lot of parts replaced in the last few years, but I don't think any of those three have been touched - all original. My last visit to the mechanic for the fuel pump was a $500 repair bill. If those parts aren't hard to get to (and I don't think all of them are) I would rather spend $100 now than $1500 later, lol.

thanks to anyone who can help me!