Good day,

I have these two codes, P0172 and P0175, I ran another thread called "running rich" earlier but haven't necessarily been able to figure this out.

The truck seems to run good even though both banks are running rich. I have ben able to spot a few consistencies with when the codes are placed. According to my code reader the codes get placed avery time around 30 MPH when I am doing in town driving. If I clear the codes and get on the highway I can drive for however long I want and the codes wont come on. Then once I am back doing in town driving and I hit that 30mph zone I get the codes.

I started by replacing the two rear O2 sensors as one had a code for the heater circuit(drivers side) and the other was not providing a voltage up to the ECU (passenger side). The one sensor on the driver side now has no heater circuit issues and the heater circuits for all four sensors go into "ready" sate for emissions testing but still no voltage from the passenger side sensor. This indicates to me that at least a part of the harness is intact as the sensor appears to be heating up.

Now here's and interesting question, why don't I get any other O2 codes if the one sensor isn't supposedly providing any data? and why are both banks running rich? If both banks are running rich I suspect that it would be caused by something upstream?

I need help to figure this out soon as I need to get this thing on the road in my name and cant do it without a valid emissions test. I keep trying to trouble shoot using a dealer plate (work for a dealer) but I need to eventually get this thing registered.

I bought this thing a year ago and have been working away at it to get it on the road. I just ordered a lift and new tires for it yesterday and a new rear drive shaft with the rotoflex delete from lucky8. All this to say I need to figure this out.

In some of my recent work I have changed the following parts that could have helped the problem:
-water temp sensor
-timing chain and gears
-PCV valve and hoses
-Brake servo hose connection at the manifold
-Spark plugs and wires

Is there an easy way to reset the computer so it does a full new adaptation as a lot of parts have been replaced that would ultimately affect the engines operation.

N.B These codes were coming up before all this work and since I bought the truck.

 

So I did a little troubleshooting tonight.

I was testing continuity in the harness C0635 that i disconnected from the back of the ecu. This is the harness that is hooked up to the O2 sensors...

The results are that: pin11 HO2S sensor LH bank - downstream Earth/ Signal 0V has no continuity.

This is a little confusing as my code reader was indicating that it was Bank 2 sensor 2 that had no voltage signal. Maybe my code reader is slightly mixed as to what is bank 1 and bank two.

My next step its to disconnect the sensor under the drivers side and see if that changes the continuity on the sensor in question therefore also affecting the signal wires continuity.

If my wire is in fact pooched is there an easy way to replace this wire?

 

Any update?

 

Not yet, things have been a little crazy the last couple of days but not to worry I will post as soon as I do.

 

I have no idea what is going on, I am starting to wonder if I just just cut out the existing wires coming out form the back of the ecu and send some new wires to the rear o2 sensors. I do get some signal from the rear o2's after all but its a very week signal. +- 0.05 V

Is there any ground point between the o2 and ecu that I could check and clean that might be affecting the signal?

my other option is to replace the whole ecu harness all together. Has anyone done this before?

 

I recently bought new sensors and two of them had the wires in the wrong location on the plugs. Was throwing O2 heater codes and was getting no voltage. If you haven't already make sure they're correct.

 

To all those who have been following some of my issues I have finally figured out this problem...

I removed the two wires going to the two rear o2 sensors and started to remove the wires all the way tot the engine bay. Where this harness meets up to the main harness in behind the engine block on the drivers side I found a mess of electrical tape and a hand full of corroded but connectors. Anyhow all this to say I am running new fresh wires to both rear o2 sensors all the way back to the ecu. should be finished sometime this week.

Cant wait to be able to pass an emissions test.