Since we're all about sharing knowledge and hopefully saving money here, I've got a cheap and easy fix to the P0473 Exhaust Back Pressure Sensor Circuit High Input code, that is a lot less expensive than a code eliminator.

As some of you may know, there is some speculation that at high boost levels, the truck will de-fuel due to high exhaust backpressure, and the backpressure sensor reading that pressure. I don't know that this has ever been proven, but it's theory, and PDP sells a code eliminator for it. I have the code eliminator, but got a little worried about it when Cat_man had some problems with his code eliminator going bad and that was robbing some serious power. So, I started looking for alternative solutions, and think I've come up with one.

When I was pulling my stock fuel bowl off, I needed to remove the EBPS to get to one of the bolts that held the fuel bowl in place. When I unscrewed it, I noticed the threads looked to be 1/8" NPT. Since I didn't use it anyway, I figured why put it back on, and just plugged the hole with an 1/8" NPT plug that I had. Simple.

Now, the only problem I had with the code eliminator is that it still tripped a code, but only one that said the EBPS was reading too low. I didn't think that would cause any running issues, and it didn't, but just keep that in mind. This evening, I took the code eliminator off and plugged the sensor back in, zip tied it to the heater core return hose in front of the HPOP, and capped off the threaded end capped off with a 1/8" NPT cap, just to keep any dirt, water, and crud out and possibly causing the sensor to go bad. I plugged the code scanner in and the code that showed it was reading low is gone. The truck didn't run any differently, but I didn't expect it to.

So, if you're getting a P0473 code (Exhaust Back Pressure Sensor Circuit High Input) and you're thinking the truck might be defueling, you do not need to buy a code eliminator to get rid of it. Just go to the hardware store and get a 1/8" NPT plug and cap, unscrew the sensor, plug the hole where it was, cap the end of it, and secure the sensor so it doesn't bounce around. A cheap and easy fix!!

 

This is interesting. I would have thought for sure that it would trip a code not seeing any pressure at all and the MAP seeing boost.
Please continue to monitor this. If it works, I'll do the same. Maybe plumb it into the boost guage line so that it's seeing some sort of pressure.

 

Great work, Jeremy. Definitely post updates on how it does with further monitoring.

 

I'm interested too, since I was about to go out and get the code eliminator for my truck. At least this way I can get rid of one out of two codes that I keep tripping.

 

I did find out this little tidbit of info:

FAULT DETECTION MANAGEMENT
An EBP signal that is detected out of range high or low by the PCM will cause the engine to ignore the EBP signal and disable exhaust back pressure operation.

The NGS tool will display a fixed PID value of 43.5 PSI (300 kPa) for EBP when exhaust back pressure is in default.

So, this means that by capping the sensor, the EBP system is now disabled? At least that's how I'm reading this. What is the high pressure value for tripping the P0473 code?

 

I found a tidbit of info. I tried to post it just a minute ago but I guess the link I provided wasn't allowed and it didn't post my reply. Anywho, it came from and article on TDS. There, I referenced it, now here's what I found....

FAULT DETECTION MANAGEMENT
An EBP signal that is detected out of range high or low by the PCM will cause the engine to ignore the EBP signal and disable exhaust back pressure operation.

The NGS tool will display a fixed PID value of 43.5 PSI (300 kPa) for EBP when exhaust back pressure is in default.

So, if I'm reading this right, by capping off the EBP sensor like jtharvey did, the EBP operation is now disabled. If it defaults to the 43.5 PSI value, is this the normal range of function for most driving conditions? What is the value that sets off the P0473 code?

 

Pocket, you got it, twice actually.

By capping it, the function of the sensor is no longer happening, but it's not disabled like tht would cause it to display the fixed value that you talk about. It's still taking readings, only now it's just whatever ambient pressures are, and not of the exhaust. The signal will neither be high or low.

I don't know for sure what the high pressure value is for tripping the code, but I would guess it's up around 55-60 psi.

 

Well, I just did this mod to the sensor today, but now I have another problem.

I can't get over 20#'s of boost. My P0478 code is completely gone now, and I can't get it to trigger another code no matter how hard I try. I did this mod because I started tripping the P0478 code even in lower settings on my chip, and much lower boost.

I doubt that this mod is causing my boost problem. JT, did you have any changes in boost after you capped the EBP sensor?

I tried diagnosing a boost leak or turbo problems. My turbo is in pristine shape, no play at all on the shaft, blades look brand new. Intercooler boots aren't leaking, and I retightened them just to make sure. I unplugged the wastegate and was able to hit 21#'s, the EGT's didn't rise as quickly, and I had less smoke. Can a weak wastegate open up even if it's unplugged?

 

I was running a code eliminator before I removed it and just put the capped sensor back on. I don't know if this would effect boost numbers or not, but I was peaking at 26 psi in both of my configurations. Now I'm wondering if it does somehow affect boost. I doubt it does, but I think I'll make sure the tube and sensor are both cleaned out, then hook it back up to see what happens. Maybe a good Monday project.

A wastegate will open up on its own, even if it's unplugged. The exhaust pressure will overcome the speing pressure and open the wastegate. You can put a turnbuckle on the wastegate to make sure it stays shut, but don't run much over 25 psi like that. The stock turbo will have too much backpressure much over 25 psi, and that can cause engine damage.

 

With my setup I was previously peaking at 28#'s. Lately I haven't been able to get on it hard because of the P0478 code that I kept tripping, so I had no idea that my wastegate was opening prematurely.

Well, I'm about to order the ATS housing anyway, might as well go with the Banks Big Head at the same time.