CEL: P0170 and P0130

[Stilllearning6]

1998 740iL :

CEL revealed 2 codes.
P0170 : Fuel trim out of range ; Bank One
P0130 : PCM not detecting proper activity from Oxygen Sensor : Bank One , Sensor One.

I am not sure of the meaning of: "proper activity".
Does that mean no signal at all or does it include voltage either below 0.1volt or greater than 0.9volt or some other range?
I am leaning toward believing no signal at all. Not sure if that is correct belief.

I am thinking that lack of proper signal from O2 Sensor Bank One / Sensor One would cause the creation of code P0170.
I am thinking that either faulty wiring from oxygen sensor or a faulty oxygen sensor would be the culprit.

I am eliminating MAF as this would cause more universal codes to be created and not be limited to just Bank One , Sensor One.
I am eliminating an unmetered vacuum leak based upon my belief that code P0130 means no signal at all from oxygen sensor.

I am thinking that the faulty wiring or faulty o2 sensor made the PCM dump excess fuel into engine in an unsuccessful attempt to raise the oxygen sensor signal from a low value ( no value at all ) to closer to 0.45volts.
But, the faulty wiring or the faulty O2 sensor will never generate a signal of .45volts , so the PCM keeps calling for more fuel.

My plan:
check for faulty wiring at Bank One , Sensor One ( free) or replace oxygen sensor at Bank One Sensor One ( $100)

Can the experts confirm / deny my reasoning?
Am I missing something?

Willing to be educated.

Can I check the O2 sensor voltage?

Looking for guidance.

[Timm]

You can use INPA diagnostics to find what is going on as described below - however, I would suspect the Lambda sensor itself as you are getting a circuit error rather than an ageing code:


https://youtu.be/CBfyCItOJH0

[Stilllearning6]

I pulled the Oxygen Sensor to check its functionality and also purchased a new back-up oxygen sensor.

The heater circuit of my original sensor showed zero resistance, same as the new sensor.
I used a propane torch to heat the original sensor to red hot.
It produced voltage , approximately up to 0.3 , once I thought that I saw 0 .7; though usually it hovered less than 0.3.
My take away was that it did produce signal.
My conclusion was that my oxygen sensor is still good.

I then felt that my oxygen sensor circuit wiring was suspect, so I attempted to check it out.

With a cold engine, I used a 12v test light that was grounded to chassis.
I started the cold vehicle and probed the 4 pins from the harness side to look for the heater circuit signal.
Result: Yes : light the 12v test light in the heater circuit.
Conclude that heater circuit gets signal. Good.

Next : test for heater circuit ground connection.
used ohmmeter from oxygen sensor harness heater circuit pin to chassis
Result: resistance fluctuated from 5-9 ohms. I figure that my ground was not perfect, so I called it a Passing grade.
Conclude : heater circuit grounding is good.

Then, started the engine and let it idle to operating temperature.

While still at idle,
I checked for oxygen sensor voltage signal output directly from the oxygen sensor (harness had to be disconnected).

Result: very difficult to read as my multimeter was losing its internal battery connection.
In spite of that difficulty, I believe that I got results that oscillated up to 0.03 volts . Very tough call to read.
I did not increase the rpm's to call for more activity. Perhaps a mistake.

Based upon this extremely low reading while at operating temperature and at idle, I am faulting the original O2 sensor as faulty.
This may be a mistake, as my bench test showed higher voltages.

Hence, I reluctantly installed a new oxygen sensor.

I started vehicle and Check Engine light appeared.
Let in run 8-10 minutes hoping that it would disappear. No such luck.
Turned off, restarted hoping the CEL would vanish.
Result: CEL still appears.

Now, I am wondering if it should have cleared itself or I need a special tool to clear the CEL or my issue still persists and it may be bad circuit wiring.
Does it need several starts/runs to resolve itself?

Any comments?

I wish that I knew the circuitry better as I want to do more testing of the wiring/connections.
The wires from the oxygen sensor disappear into the chassis behind panels and vanish.

[acspecialists]

Listen to Timm.

The CEL will clear with software, battery nap or enough key cycles. INPA is free an the cable is $35. If you want to own one of these cars it is the first thing to acquire. A multimeter is good for checking the voltage of the battery at the battery. For example the the spark plug coils always have power and only fire through the DME grounding the circuit through a transistor.

[Stilllearning6]

Based upon posts in this forum, I disconnected battery for 30 minutes.
Reconnected battery.
Started engine.

Result:
No more Check Engine light.

Let idle for 4 minutes to operating temperature, still no light.
Perhaps drive it tomorrow.
Thank you all for guidance.

I plan to get that INPA software, appropriate cables, adapter for 20 pin engine connector.
I don't know anything about INPA and just started to read some info about INPA.
I did not know that it is free.
I found an internet ad offering INPA for $45 with "support", IIRC.
Don't know if free is better.

[acspecialists]

https://www.bimmergeeks.net (https://www.bimmergeeks.net/)

https://www.bimmerforums.com/forum/forumdisplay.php?233-Diagnostic-Software

Just buy the cable