Dead battery Gas sensor reset?

Maintenance/Repairs
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Hi there,

It’s a 2010 Nissan Teana 250XV, model J32, should correspond to a Nissan Maxima.

Service manual states that when you remove the battery the gas sensor needs to be adjusted? Something to do with how well the driver can smell may need adjustment? What is this sensor?

Tried to Google it but couldn’t find anything. Do find some info stating fuel mix ratio maybe off afterwards in some cars?

If I replace battery what settings will be lost?
On YouTube there’s videos on using a 2nd battery to connect positive terminal to and the negative to a metal part, before disconnecting the old battery, so the car never loses power, hence no settings are lost, is this safe/advisable?

Many thanks for any advice,
Best regards

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https://www.aa1car.com/library/battery_disconnect_problems.htm

Tester

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Use a 12V memory savery

Yes, it is safe

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thanks a lot for the advice.

Ok, I have found memory savers available online, but they all need to be connected to another battery with clamps… I do have a powerbank that I use for jumpstarting, but it delivers 15V, so this may be too high? I doubt I can fit the clamps on a 9V alkaline battery (I noticed in above link some memory savers come with that connection)

In regards to what would happen when the battery would be disconnected and the car would lose all power, since this is an older car of 2010, with a naturally aspirated V6 engine, not much settings can be lost? not like with the new cars where it’s all computer steered?

From the Service manual of my car I only worry about this one:

It’s part of the “Automatic temperature control”:

Gas Sensor Sensitivity Adjustment Function

it’s part of HEATER & AIR CONDITIONING CONTROL SYSTEM chapter:

DESCRIPTION
According to customer’s sense of smell, gas sensor sensitivity can be changed

Adjustment: Less or More sensitive setting than normal setting (REC later than normal operation.)

NOTE:
When the battery cable is disconnected from the negative terminal or when the battery voltage becomes 10 V or less, the setting of the intake switch memory function may be cancelled.

Think I figured it out to some extend: the aircon can choose to recirculate the air - REC setting or to take in outside “Fresh” air - FRE, so this sensor will determine when it’s set to automatic when to open for outside air or when to recirculate. Since I’m in Bangkok I always have it on recirculate, and so far it never changed automatically (it was once reset when I lost all battery power after not driving for more than a month…)

Audio_system
Audio_system905×1210 289 KB

but what gas are we talking about here?! this gas sensor is measuring what? CO2? TVOC?

(according to the manual other settings that would be lost are no biggie: temperature fine tuning, window auto-up (fix is easy) and driver seat assist (seat moving backwards to get out, which by the way all still work after I once had a completely dead battery)

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Here’s the memory saver I use. It has an internal 12V battery

image

There are lots of different brands and thus varying prices

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That’s a good question. I’m not seeing any “Teana” model listed for 2010. Are you outside the USA? For the Xterra 4L V6 there’s only two fuel sensors, one for level, one for temperature, but both are located in the area of the gas tank. So I can’t see how those would affect fuel odors noticed inside the passenger compartment.

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He/she/them said they are in Bangkok, so not likely they’ll have a professional memory saver available. A cheap memory saver just plugs into the accessory jack with a 9 volt radio battery. Just enough to feed the computer while disconnecting the battery.

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So after connecting the battery push the button to make your selection.

Most Lexus vehicles have a pollution sensor in the grill for HVAC operation, there is nothing to program after replacing the battery, the system resumes operation after replacing the battery. I doubt that your Nissan’s A/C system will be crippled after replacing the battery.

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yes, Thailand, also in Japan called Teana, it’s the most premium Nissan sedan in Thailand (and one ugly beast, haha, but I like it because this older model still has the V6, love this engine combined with the CVT, the newer models all 4 cylinder…), corresponds more or less to a Maxima, actually the Maxima A35 (2009-2014) has the exact same center console with AC and radio.

ok, I finally found more info in the Service Manual:

SMELL OF EXHAUST GAS INPUT PROCESS
Gas sensor detects ambient atmospheric CO and NO2, and converts them to values of resistance. The values are converted to signals with the gas sensor internal circuit, then auto amp. inputs the signals.
https://zinref.ru/avtomobili/Nissan/033_10_00_Nissan_Teana_J32_2008_year_Manual_ENGLISH/701.htm

(I cannot change any settings, can only be done with the Nissan diagnostics device CONSULT-III)

I believe this sensor can then decide to open the outside air, or to recirculate the cabin air. Since I’m in Bangkok with very bad air, I keep outside air out at all times.

So I can conclude if I were to smell exhaust air I should have it adjusted, hehe.

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CO has no odor, but NO2 does, pungent smell. Not car related, but years ago I used some sort of gas sensor (CO2 I think) and I recall each time I used a new sensor it had to be calibrated to the instrument I plugged it into. Each new sensor came with a small glass vial that had a known concentration of the gas, and I had to connect the sensor to the vial, then adjust the instrument so it read the correct ppm as printed on the vial If that’s the case for your car, you’ll have to have that done by a dealership b/c even if you could adjust it yourself, you have no vial of known ppm to calibrate against.

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Most sensors now are factory calibrated. They store the cal factors in non-volatile memory like an EEPROM. It eliminates the cost of manufacturing and distributing calibration standards for every sensor made…The ability to tweak the trigger thresholds may be protected from the casual user. So they need a scan tool or similar to adjust the detection threshold but not to field calibrate it…

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A solid state gas sensor is inexpensive and will respond to many gases. But unless calibrated with a known concentration of gas on a regular basis they will not be accurate. They will detect a gross leak and in a consumer application (vs industrial) usually good enough.

http://intlsensor.com/pdf/solidstate.pdf

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Requiring periodic calibration would be a non-starter for the car market. These MOS type detectors have an inherently linear output. So a simple calibration scheme can be employed. They don’t need to be laboratory instruments measuring absolute concentration. So small offset errors don’t really matter. They can simply look at the slew rate on the sensor output to know if there is a reason to close the air inlet. Check this out-

Key features of both reducing sensing and oxidizing elements are that the sensors are stable, repeatable and have a response time of seconds. MiCS has also developed an AQM module that includes its dual AQM gas sensor. As shown in Fig. 7, the module is extremely small and can be seamlessly located within the HVAC to automatically control the ventilation flap. The AQM module maintains the ventilation flap in the open position. The flap is closed only when high concentrations of pollutant gases are detected. Intelligent algorithms based on sensor signal rate of change efficiently achieves this, without the need to calibrate the system to absolute gas concentrations.

High level overview from Nissan (looks like perhaps and earlier implementation looking at O2 concentration only)- Forest Air-conditioning System | Innovation |

I have been involved in the design of non-dispersive IR absorption spectroscopy systems for both medical and industrial applications for more than 25 years. We make a number of systems currently for industrial gas monitoring (explosive gas monitoring on oil rigs, ocean going ship emissions, smoke stack monitoring etc) as well as indoor air quality. They are not as appealing as a MOS type detection system in automotive applications due to their relatively higher cost but they can measure even lower absolute concentration levels without the need for any periodic calibration and are impervious to background gases and humidity.

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The gas sensors are mounted behind the grill and don’t need to be terribly accurate to detect vehicle exhaust gas. The HVAC controller chooses fresh air or recirculate bases on the input of the gas or pollution sensor, since the OP keeps the system on recirculate all the time this senor isn’t a factor.

Where did the air inside your car come from?

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They may find that the car will not allow you to have it on recirculate all the time. Some of the newer designs I’m seeing coming out are testing both external and cabin air. They don’t want hypoxic conditions in the cabin either and may force the flap to outside air even though it may not smell good…I can’t wait to see the bipolar reaction of these systems when neither option is good… :stuck_out_tongue_winking_eye:

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During the 1990’s Chrysler owners were complaining that the ATC controller would keep switching to fresh air and they would have to push the recirc button again. The engineers had placed a 10 minute limit on recirculate so that the passengers wouldn’t foul the evaporator coil. Many people today keep the system on recirculate all the time, there are many stinky A/C systems.

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@TwinTurbo I worked for MSA - gas detection side - for 30 years, who do/did you work for?

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exactly, you can only adjust the sensitivity setting, like from -3 -2 -1 0 +1 +2 +3

hmmm I didn’t know recirculating the air is so bad for the AC, fouling can happen more quickly?
I do try to replace the cabin airfilter now and then (which is a pain in the a…, need to literally sit upside down and reach below/behind the glove box, need to be an acrobat, the old one I found was put in there crushed in a terrible condition, believe 40% of the air was not going through it)

and I have done once a disinfection (Sonax product, it’s a can that sprays empty in your car, need to put AC on max and let it work some time), but indeed I still get some smell when the car starts blowing, so guess will try to open the outside vents now and then when outside air is good

still have another product with a fine tube that you’re supposed to spray inside the air ducts, but I’m a bit hesitant to do that, could be abrasive or damage the ducts / AC?

@Nevada, indeed the sensor is behind the front bumper somewhere.
Haha, yeah it’s all outside air to some extend, but at least the one coming through my cabin filter is clean(er), and I’ve measured with a 2.5pm particle size tester always low values, so my inside air is at least free from particles…

So recirculating can cause dangerous levels of CO2?

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I will send you a PM. I am quite familiar with MSA…
:wink:

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Cars have always been designed to have a fresh flow of air to reduce the possibility of hypoxic conditions developing in the cab. Most require vehicle movement to accomplish this. Now there is a trend to make cabs better sealed for exactly the conditions you are experiencing. So they need to include a provision to prevent the recirc mode from being continuously set in the event of a drop in O2 levels in the cab…there is a trend in the industrial market to detect CO2 levels in office spaces for the same reason…a byproduct of thermal efficiency…

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