uFluidics

Hi all,

I'm hoping someone can help me solve this issue.
I've replaced all three oxygen sensors. I checked the wiring, and it looks ok. I've used a multimeter to confirm that the sensor is getting voltage.
I have a new y pipe, I've cleaned the MAF and throttle body, and I have a new fuel filter. I've tried three different oxygen sensors for Bank 1. I still have this low voltage issue.

On the highway, it will operate in a closed loop, but the Bank 1 sensor fluctuates at much smaller amplitudes (0.2-0.4). On local roads, it reports open loop due to system failure, and the Bank 1 voltage stays around 0.3. Sometimes it reports open loop due to insufficient temperature, and then switches to system failure.

Fault Codes:
P0400 - Exhaust Gas Recirculation Flow
P0325 - Knock Sensor Circuit Malfunction
P1148 - Closed Loop Control Function Bank 1

Any ideas?
(See images)

Thanks,

uFluidics

uFluidics

Is it possible that there might be a clogged bank 1 fuel injector?
I can't imagine that the EGR problem would affect the oxygen sensor's voltage

JvG

There are ground wires on engine between the uim and the front valve cover. A bad ground could create a low voltage situation. So clean the grounds with sandpaper, see what if any effect that might have.

Also clean the terminals of the fuse for the oxy sensors.

maxprivate

iTrader: (12)

could be a problem with the exhaust system itself?

uFluidics

I've attached a photo. Would you mind having a look and telling me if the two bolts circled in red are what you're referring to?

The car runs great, and it's super fun to drive. I would think I would experience something more than just reduced fuel economy if there were an exhaust system problem, right?

uFluidics

Sort of off topic, but might be related. Three of my headlight bulbs just stopped working. Only my passenger side low beam works. Brand new fuses, brand new bulbs all around - do you think the oxygen sensor showing low voltage and the headlight bulbs not working have a common link?

JvG

I don't see have the oxy sensors and the lights have anything in common.

Strictly coincidence.

Unless...... do you live in an area where road salt is used? Are your contacts corrodeed?

This factor could explain both issues.

uFluidics

I didn't think they were related, either, but figured I'd ask. I live in New Jersey, so we definitely have road salt every winter. I have a brand new battery with a brand new ground wire. I doubt that's the corroded contact.

I hope I won't have to open up the engine harness to go hunting for the break.

JVG, so those two bolts circled in red are the ground points, right? (Referring to the picture in post #5)

JvG

Oh boy, does it look nasty and corroded under the hood!

The screws I'm talking about ar at the base just to the right of the second intake tube from the left.

Remove those screws. Perhaps a bit of leverage with some vice grips could bust them loose.

Sand the contacts under there, with 600 grit sandpaper. Also the engine where that screw goes.

Here is a concept. The injection system gathers information from various sensors on the engine.
Some of the measurements invlove measuring resistance. Corroded contacts have more resistance than clean ones. So the resistance from the corroded contact is basicly sending incorrect info to the computer. The computer, in turn, reacts to the lies it is being told. So the engine won't run right.

Light bulbs need a certain amount of amps to work properly. They might get 12v if you measure. But it's amount of electricity it gets is limited by th corroded contacts. Look for corrosion in the light bulb sockets, on the light bulb it's self, and also trace where the ground wire meets the car body somewhere. That's why you see cars with dim headlights on one side, or both sides. Not enough electrical power is getting through.

I used to live in Salt Lake City. Lots of road salt there. So I learned about this the hard way.

Once I moved to Portland, where road salt is not used, I noticed how little the cars rusted and corroded. Even though we get 40 inches of rain here.

I was having weird issues with my 92 Nissan pickup. Engine would idle high whenever it was moist outside. But would run perfectly during our dry summers. I finally read a post which mentioned a dealer service bulliton which mentioned a set of wires joined with a copper staple. Which corroded.
Easy fix.

uFluidics

Oh man, thank you for the insight. I looked under the hood and saw a bunch of green on the headlamp grounds (two bolts - one on each side of the car). I'll clean up the contacts and post an update in a few days. Thanks again, JvG.

uFluidics

Update:

JvG, I cleaned the ground contacts for the headlight bulbs, and that got both high and low beam to work on the passenger side. Unfortunately, that didn't cut it for the driver side. I ended up intercepting the grounds at the copper staple you mentioned, and I connected a new wire directly to the battery. Sloppy job, but it's all working for now.

Hopefully, I can get the o2 sensor to work tomorrow.

JvG

Incremental progress is still progress.

You are learning a set of skills which will be useful long after the Maxima has come and gone.

uFluidics

Yes, this max did get me jump-started on building up my repertoire of tools.

In order to fix the oxygen sensor ground, I cut the middle black wire from the sensor side and connected it to a new ground wire. Unfortunately, that black wire from the sensor was NOT the ground wire .
This made me realize that the front sensor is actually bank 2, not bank 1 (bank 2 sensor immediately failed). My problem this whole time was with the rear sensor, and I had replaced the front one three times, thinking that I was having bad luck with eBay sensors. I swapped in 2 of the eBay sensor's I had from a few months ago, and all is well now.

Thanks for the help, JvG.

JvG

Easy to get confused.

I myself replaced both oxy sensors on the engine.
Mostly because it was time to. The car ran great.

Till one time close to emmissions inspection last fall. Cel light on for a sensor I had replaced not that long ago. Replaced that one. Only to find that the light was still on. I parked the car for the winter, and worked on other projects.

This summer I wanted to get the car back on the road. Seems that elves, gremlins, or my inattentive self had removed the oxy sensor fuse. So the cel was on. Duh...... Replaced fuse. No more cel.