2001 Niss2001 Nissan Maxima (California) Stalls in Park, Has P160 code sel light

[pcumming]

2001 Nissan Maxima (California) Stalls in Park, Had P0160/P0158 code + sel light

I have been trying my best to research this and seems there is not a single solution that will fix my issues. Car been at 2 independent mechanics and prob not solved. Last mechanic said he will not charge me much until he can resolve this. I asked Nissan about this issue and they said it could be anything.....

I have read a lot about the 01 Maxima's and the plethora of SEL/Emission issues it has along with the expensive things people have tried to resolve them, part by part replacement. II read in some forums and a mechanic also said that the 2001 ECU will sometimes show the incorrect code for what the problem truly is.

Appreciate any help. My mechanic will be researching more next week and talking to Nissan and others. Am unemployed and cannot afford to replace a ton of parts until we find a real solution.

PROBLEM:

Stalling in Park/Neutral while engine hot-normal idle RPM is about 650-700

1. Car will stall occasionally while in park or neutral. If you rev engine up to about 5k RPM's and let foot off accelerator (in park/neutral), car will occasionally stall. Will not happen while in drive. No code thrown in ECU.

What work has been done in past: Cleaned current Mass Air Flow Sensor, had fuel injectors professionally cleaned a while back (15k miles), had new coil pack put in and new plugs (15k miles). Stalling has gotten more frequent. Had ECU reprogrammed in last day, had 2 (of the 4) O2 sensors replaced (by mechanic) with Nissan parts prior to Nissan ECU programming.****Not sure if Nissan put ECU in self learn mode (could be an issue????)

Mechanic put the diagnostic scope on it and got it to stall a few times again today and to him the diags looked normal. Did not get lean code but have heard ECU may show wrong codes for 01 Maxima's.

Stalls with or without P158/P160 codes I recently got, see #2 below.

2. After 15 minutes of leaving mechanic today, the SEL light came back on. Only code P0160. this time. Had code of (P0158/P0160) 3 days before.

As mentioend above, I had 2 sensors replaced with Nissan parts. .Mileage is fine, car runs fine otherwise. Cannot get inspected in NC with SEL light on unless it goes off and stays off for 100 miles. Inspection due in a few months.

I have read posts that said perhaps SEL light and or stalling could be due to: Throttle body, MAF sensor replacement (I had it cleaned), replace all 4 O2 sensors, new coils (done 15k ago), idle air control valve, fuel pump, replace camshaft(crank) position sensor, clean throttle body, replace throttle body and/or sensor(?), vacuum leaks (should show in ECU?), etc.. Obviously do not want to replace everything....If it were a lean code, I would get a different code I would think and then have to change something (ideas)-Mass Air Flow or ??????I think I am getting the wrong code. Had another mechanic use his reader and got same code as my mechanic.

Thanks so much for an answer I hope that may remedy the above 2 issues.

SincerelyPeter
Modified by pcumming at 12:11 PM 1/9/2010

[loystock]

I can understand your frustration, having spent a bundle replacing coils and plugs, O2 sensors and injector cleaning. The stalling when in Park/Neutral but not in Drive may or may not be related to the O2 sensor problem. So let's see if we can spare you from additional expenses.

Let’s look into your Bank 2 Rear O2 sensor (HO2S2-B2, where HO2 refers to Heated O2 sensor, S2 for Rear Sensor (S1=Front) and B2 for Bank 2 (B1=Bank 1)) issue. Having P0158 (consistently LOW (LEAN Air-Fuel mixture) voltage even at high RPM) and P0160 (abnormally HIGH (RICH A-F mixture) voltage is a paradox by itself. So here are the possibilities about the O2 sensor problem:-the mechanic replaced the wrong O2 sensors. I have seen this happen before as people tend to get confused about the actual location of HO2S2-B2 sensor. In the Maxima with transverse V6 (VQ engine) installation, Bank 1 (right) for cylinders 1-3-5 are closer to the firewall while Bank 2 (left) for cylinders 2-4-6 are towards the radiator. So the HO2S2-B2 is mounted on the front vertical exhaust pipe (Bank 2), downstream of the Pre-Cat, with a RED harness and a 4-wire connector near radiator (2nd from left, besides the HO2S1-B2 connector with Blue harness).-the replacement O2 sensor was mishandled/dropped prior to installation. The ceramic zirconia sensing tube is fragile and can get damaged easily when dropped.-the O2 sensor is fouled up with oil or other contaminants. So check the condition of the Rear O2 sensor as mounted on Bank 2.-vacuum leak at the air intake or leak at the exhaust. This can contribute to stalling problem so male sure all vacuum fittings are tight.-wiring (harness or connector) and/or grounding problem. Remove, clean and reconnect the main engine harness ground points (2 each, mounted near intake plenum close to cylinder #2). Checking of the harness is complicated and covered later.-fuel pressure (due to failing pump or dirty fuel filter). This is less likely since you only have stalling in Park/Neutral but not in Drive. To check fuel pressure, it requires a Fuel Pressure Gauge T-eed between Fuel Filter and Fuel Rail (34 PSI with engine at Idle; 43 PSI with Ignition ON, engine OFF).-Faulty fuel injectors (may cause Rich or Lean A-F mixture). We’ll assume they are good (separate testing required).

An O2 sensor is a chemical generator that detects the level of Oxygen at the exhaust and provides an output between 0-1.1VDC. The ECM only uses the O2 sensors (close loop) after the engine has warmed up. The O2 sensor has a heater element to facilitate warm up. In the 01 Maxima, there are 4 O2 sensors with each Front O2 sensor mounted before the Pre-Cat while the Rear O2 sensor is after the Pre-Cat. There is no O2 sensor downstream of the main cat (Catalytic Converter). At Stoichiometric condition (Ideal Air-Fuel ratio of 14.7:1), the sensor generates 0.45VDC and swings between Rich (>0.6VDC) and Lean (<0.3VDC). Since the Rear O2 sensor is downstream (after) of the Pre-Cat, its voltage swing is slower than the Front due to O2 storage capacity of the Pre-Cat. If the output, as seen by the ECM is consistently high (>1.1 VDC) at Idle or Deceleration, P0160 fault code is generated. If the output is consistently low (<0.56VDC) even at high RPM (up to 4000), then the ECM generates P0158.

A P0160 (abnormally high voltage), >1.1VDC) fault code can be caused by bad O2 sensor or an open short in the harness/connector. P0158 (consistently Lean mixture, <0.56VDC) is more complicated and can be caused by – bad O2 sensor; intake/vacuum leaks; bad harness/connector; low fuel pressure; and bad fuel injectors Since the coils and plugs are new and you don’t have any ignition-related problem, we can safely assume they are good.

If the O2 sensor is not contaminated and there is no air intake/vacuum leak; no exhaust leak no fuel delivery, injector nor ignition problem, a wiring check is required, preferably at the ECM connector (possible to do it in the O2 sensor connector but the wiring can be pinched badly).The HO2S2-B2 sensor has a 4-wire connections as follows:-Pin 1:O2 sensor output signal (0-1.1VDC) with WHITE (W) wire and connected to ECM Pin 71-Pin 2: O2 sensor HEATER monitor (0-Battery Voltage) with Red/Blue (R/L) wire and connected to ECM Pin 4.-Pin 3: O2 sensor HEATER POWER (Battery Voltage with Ignition ON) with Red/Yellow (R/Y) wire to Ignition switch.-Pin 4 is the GROUND with a BLACK (B) wire.-Pins 1 and 4 are shielded with the shield grounded thru Joint Connector-17.Use the link provided and look into page EC-249 for wiring diagram;

http://www.nicoclub.com/FSM/maxima/2000/ec.pdf

Use a voltmeter to check the O2 Sensor signal from ECM Pin 71 to Chassis Ground (DO NOT USE THE ECM GROUND). The testing can be done on Pin 1 (white wire) of the O2 sensor connector but caution is required. With the engine warmed up (2 minutes minimum), rev the engine up to 4000RPM (rev and release; do not hold high RPM))multiple times and see if the voltage swings normally (<0.3 to 0.45 and >0.6VDC). If the voltage remains LOW or HIGH continuously, then it’s most likely a bad O2 sensor or harness problem. Use an ohmmeter to check continuity between Pin 1 of O2 sensor connector and Pin 71 of ECM. Verify Pin 1 (sensor) and Pin 71 (ECM) are NOT GROUNDED . Verify Pin 4 of O2 sensor is properly grounded.

Now for the stalling problem at Idle in Park/Neutral, it could be due to MAF sensor (and its connections to ECM), dirty or failing IACV, leak/restriction in the air intake, fuel delivery or injector problems. Check and ensure the entire air intake is clean – air filter, MAF sensor (cleaning done) and throttle body and plate. Make sure you also clean the MAF sensor connector as it can be dirty and then use dielectric grease. Verify no vacuum leak (use carb cleaner and spray around vacuum fitting) and no exhaust leak. The MAF sensor may have a failure in the internal circuit (cracked board or loose connection). To check, with the engine at Idle, tap the MAF sensor close to the connector and listen for engine response. Lightly rev the engine and hold then tap the MAF sensor and listen for engine response. If the engine response changes whenever the MAF sensor is tapped, it is failing and needs to be replaced. This may not necessarily trigger a fault code. However an open/short circuit in the MAF sensor will trigger a fault code.

Good luck

[pcumming]

Thanks so much. An incredible reply. I will pass this on to the mechanic and hope they have the knowledge to handle all of this. I am not sure even Nissan would go through all of this trouble, know how, etc...

I have a few newbie questions for you based on about 3 hours of research today. You answers I will also pass on to mechanic.1. Could the O2 sensor fuse be blown in the fuse panel?2. How does one best check for a vacuum leak or an exhaust leak specifically without any codes?3. I guess it is possible a coil could be bad or an injector be bad.I read how to test coils, but perhaps you have a better way.Also is there a way to test an injector?

Or is it all in the manual pdf you so kindly gave me a link to??If you lived near Charlotte, NC, I would bring the car to you.Is it possible for a small fee for the mechanic to call you if he has any questions problems next week? (answer via private message please [email protected])

Thanks so much/Peter

[pcumming]

loystock,One other thing I forgot..Is it possible that Nissan who did the ECM update to be safe (for my independent mechanic) SHOULD HAVE put the ECU into self-learn mode?Not sure that was done.

Here are some things I thought about after reading about 240 posts prior to your reply. Any comments???

-I think there is an O2 sensor fuse, check for such in fuse panel-may be more than 1. -Ensure ground wire is connected to Cat.-Check to see that the connectors on MAF sensor are registering voltage before replacing sensor. Could be a bad connector. Please see this http://en.allexperts.com/q/Nis...F.htm-Check to see if any cracks in Cat or Manifold***-Please Replace MAF sensor -Definitely Remove and Clean Throttle Body, I would appreciate it.-Definitely Clean Idle Air Control Valve for carbon build-up-Prob good idea to check the 6 engine coils, can be done with a meter or something per the below See http://www.ehow.com/how_491236....html

******Did Nissan put car in self learn mode after programming ECU? If not, I was told they should have and this could be a problem.

-------------------------------------Step 2

-Replace Throttle Position Sensor?-Check EGR Valve, clean if necessary-Vacuum leak can cause a stall

----------------------------Step 3-Clean manifold for carbon build-up-Replace crank/cam position sensor-Replace other 2 O2 sensors

-Replace CAT????? <---------------- Get another car after get a job-am out of work

[loystock]

Please see my response below, one at a time. Please do the most simple and cheaper ones first before going into complicated/expensive items.

I have a few newbie questions for you based on about 3 hours of research today. You answers I will also pass on to mechanic.1. Could the O2 sensor fuse be blown in the fuse panel?- Not likely. The fuse is primarily for the heater to warm-up the sensor. If there is short/open circuit in the heating element, it will trigger a different fault code, e.g. P0161. But there is no harm in checking the fuse.

2. How does one best check for a vacuum leak or an exhaust leak specifically without any codes?-It's already in my previous answer. Use a carb cleaner to and spray it on the vacuum tube/hose/fitting on the air intake (the area from air filter box to the TB going to intake plenum). If there is a leak, the carb cleaner will make the A-F mixture rich and the engine will tend to surge. For exhaust leak, car must be on a lift and check for for obvious cracks/holes or loose fitting on flanges, etc.

Please go thru the Maxima/I30/I35 FAQ 'sitcky' (link below) as there are a lot of "How To's" there, including Fuel Injectors.. But do not use the one for O2 sensors as the procedure there applies to Federal Configuration with 3 O2 sensors- 1 on each bank exhaust pipe and 1 downstream of main cat. (99 CA-Config and 00 and beyond Federal-config have 4 O2 sensors). Your car is 5thGen Maxima (200-2003).

zerothread/219453

3. I guess it is possible a coil could be bad or an injector be bad. -We can do this ONLY if the preliminary procedures I have given you did not work. These 2 items are more complex. The fuel injector problem will typically show up in various RPMs. Basic checking used is the click-test (use a mechanic's stethoscope or long screw driver) and listen for clicking sound coming from the injector. Additional testing and replacement procedure is in the FAQ sticky. As for the ignition I just sent another member a procedure to diagnose ignition problem. Below is the link. Look for my response to SVTCOBRA.

zer...-code

I read how to test coils, but perhaps you have a better way.Also is there a way to test an injector? -see above.

Or is it all in the manual pdf you so kindly gave me a link to??If you lived near Charlotte, NC, I would bring the car to you.Is it possible for a small fee for the mechanic to call you if he has any questions problems next week? (answer via private message please [email protected])

-The manual is in PDF so you can print the relevant pages, especially the Wiring Diagram (HO2S2-B2) and some of the testing procedures. This is the same FSM (Factory Service Manual) that is used by Nissan technicians.

-This is NICO and we provide assistance for FREE. All we ask from members is to buy parts from our sponsors so we can keep this site working, e.g. "infinitipartUSA.com" which sells OEM parts @ 25% off MSRP. We also encourage members to have their friends with Nissan/Infiniti cars to register with NICO. I usually respond this forum at night time and during weekends. So if there is a query, post it here and I'll try to respond ASAP.

One other thing I forgot..Is it possible that Nissan who did the ECM update to be safe (for my independent mechanic) SHOULD HAVE put the ECU into self-learn mode?Not sure that was done. -They probably just reset the ECM or maybe an upgraded program. The ECU (or ECM) has self-learning feature so it can make changes when components, especially emission-related are replaced. Just drive on city streets for several minutes and then on the highway and do several WOTs (Wide Open throtyle, but do not overspeed).

Here are some things I thought about after reading about 240 posts prior to your reply. Any comments???

I think there is an O2 sensor fuse, check for such in fuse panel-may be more than 1. -see answer above

Ensure ground wire is connected to Cat. -The O2 sensor housing is grounded to the cat. The cat is connected to the engine thru the exhaust manifold. There could be additional ground points. But it is very important to check the main engine harness ground point (near intake plenum) as poor connections could cause starting and stumbling issues.

Check to see that the connectors on MAF sensor are registering voltage before replacing sensor. Could be a bad connector. Please see thishttp://en.allexperts.com/q/Nis...F.htm-I already gave you basic cleaning and testing procedure. Just a simple description, the MAF has a heated sensing element whose current changes as a function of air mass entering the sensing element. DO NOT TOUCH THE SENSING ELEMENT. The higher the air flow, the greater is the cooling effect on the sensor so the current is increased (higher voltage across) to compensate for the heat loss. When taking measurement, make sure you use the chassis ground (and NOT THE MAF SENSOR GROUND as it can damage the sensor circuit). Also, the engine must be at no-load condition (AC off, no lights/radio) and shifter in NEUTRAL. Use Pin 1 (W-white wire, which is connected to ECM Pin 61)) and measure the voltage with respect to chassis.engine ground as follows: Idle = 1.2-1.8VDC; 2500RPM=1.6-2.2VDC. Refer to page EC-134 (P0100) for detailed info.

Check to see if any cracks in Cat or Manifold - covered above

Please Replace MAF sensor - do not replace unless confirmed bad. An OEM part is expensive but a refurbished one from Napa is @ $70.

Definitely Remove and Clean Throttle Body, I would appreciate it. -already suggested before

Definitely Clean Idle Air Control Valve for carbon build-up - already suggested before

Prob good idea to check the 6 engine coils, can be done with a meter or something per the below - I provided the link alreadySee http://www.ehow.com/how_491236....html

******Did Nissan put car in self learn mode after programming ECU? If not, I was told they should have and this could be a problem. - discussed before

-------------------------------------Step 2

Replace Throttle Position Sensor? possible but usually shows as a stumbling over a wide range of RPM.

Check EGR Valve, clean if necessary - testing and cleaning can be done together with the IACV cleaning.

Vacuum leak can cause a stall - already discussed before

----------------------------Step 3Clean manifold for carbon build-up - that's gonna take a while, if you want to do that. I don't think that is the problem right now.

Replace crank/cam position sensor - possible but should show up on a wide range of RPM. Car may not even start.

Replace other 2 O2 sensors - No need unless the fault code is specific to that sensor.

Replace CAT????? <---------------- Get another car after get a job-am out of work - LAST RESORT DUE TO EXPENSIVE PRE-CATS AND CAT. There are 2 Pre-ccats (for Bank 1 and Bank 2) and 1 main cat (rear) and OEM parts are really expensive due to precious metals inside (Platinum, Palladium and Rhodium. Aftermarket parts are cheaper but don't last long. A continuous RICH mixture will destroy the cat (unburned fuel will ignite inside the cat and destroy the honeycomb)). If Bank 2 Cat is bad, the catalytic oxidation/reduction and O2 storage capacity will be impaired. So the Rear O2 sensor and the Front O2 sensor (if they are operational) will have similar voltage swings (same level of O2 detected by both sensors).

Whew...this is the longest one I've ever done so far...

[pcumming]

You're the best. I have a lot to go on now and to present to the repair shop including the entire 560 page manual being printed at Office Depot.

Thanks so much!!!

Peter

[loystock]

I thought you want to save money? Just print the relevant pages or if you want, the EC (Engine Control System) chapter only.

Again, start with the most simple and cheapest route before going to the complicated ones (which I outlined in the original response).

[pcumming]

An update on how my stalling and SES light problem may be solved thus far. Got car back from shop a 2nd time.First time they replaced 2 O2 sensors, and had Nissan reset the ECU.Car still stalled and SES light came back on in 15 miles.

Took car back 2nd time and they replaced Mass Air Flow Sensor with a new one (my cleaning old one did not help). They found another code for a 3rd (of the 4) O2 sensor. That was replaced. Now all seems well---for now..

So I am all set. I guess if it occurs again, perhaps will replace last O2 sensor, clean/replace IACV and clean Throttle Body as you had suggested.

Thanks again!!

Peter

[loystock]

I'm glad the 'bleeding' is over and I hope your car stays that way. So we're on track when we narrowed down the problem to O2 sensor(s) and MAF instead of 'shotgun' troubleshooting.

[pcumming]

Well may not be over yet..

I had constant electronic motor mount whirring and read on the Nissan Forum that if you do not replace the motor mount then it could eventually fry the ECU as a few people had pointed out. http://forums.maxima.org/showthread.php?p=7378916

When I picked car up today I heard the whirring again. I thing the mechanic unplugged the front instead of the rear electric motor mount. So I unplugged the rear. To get at it, I took off some air cleaner duct shroud to get at the rear motor mount connector. I unplugged connector going into air duct. I then started car and shut if off a few times to ensure all was well and no more whirring sound.I then got a Check Engine Light. Crapola...So I unplugged the battery and will let it sit overnight to clear code for now.

At least they got it to pass inspection (North Carolina) while SEL light was off. Mechanic drove the car enough miles for ECU to cycle and pass inspection with no codes. Good for another year.

Guess I will do nothing till next years inspection if light is still on.

****My question is: Could my restarting the engine a few times with rear motor mount unplugged and whatever sensor (ambient temp sensor perhaps?) is in the air cleaner duct unplugged cause the sel light to come back on? Or just coincidence?I do not care to have the OBDII code pulled from the ECU since it passed inspection.Thanks again for your expert advice and kindness of course


Modified by pcumming at 2:00 AM 1/16/2010

[loystock]

I have to edit your post. I am sorry but you cannot make a link to a competing forum. Info about engine mount is also available in this forum, as in the link below

zerothread?id=465361

AFAIK, disconnecting the connector for the engine mounts should not trigger a CEL. However, the Air Inlet Temp sensor is used in conjunction with the MAF and other sensors by the ECM to adjust fuel injector pulse width. So disconnecting the AIT sensor will trigger a CEL.

IMO, ignoring a CEL is not a good idea. It may lead to a bigger problem, e.g. O2 sensor problem can lead to catalytic converter failure.