NATS Immobilizer & No-start: P1610, P1614 (2022)

Rocketman HI I have same problem can you MI give extra information. What can I do

I have a will crank but no start problem with my 2001 Sentra SE with the 2.0 liter engine. Miles = 133 K. I bought the car new. A few days ago it would not start for the first time ever. Crank but no start. Had a weak battery in it at the time. It was a mild day in the 50’s F. I started the car and moved it from the basement garage to just behind my home. It started and ran fine as was normal. I did not let it fully warm up before I shut it off. A few hours later it would not start using the same factory key that came with the car. First time I tried to start it, it cranked only. Turned the key off and tried again and it fired on maybe two or three cylinders for a very brief second. Tried a third time and again only a very brief firing on a couple of cylinders. Since then only will crank with no sign of firing.

Used an OBDII code reader and found no old codes but two pending codes P1610 and P1612. Looked these codes up and find they are for the immobilizer system. The code reader called it the NATS system. My owner’s manual calls it the NVIS system. For what it may be worth the car has never had a check engine light.

Here is a summary of what I have tried and found so far.

- Installed a new battery. The battery which was in the car at the time of the no start was weak and old.

- Used a scan tool in the OBDII port and looked for codes.

No old codes

at all. Two pending codes showed up P1610 and P1612.

- Pretty sure there is no spark. Tested with a timing light and pulled a sparkplug and got no spark.

- Not sure about the fuel pump as there in no fuel rail valve to hook my test gauge onto. I cannot for sure hear the fuel pump ramp up. One person, a locksmith, says he heard the pump. I took the back seat out and the floor cover off above the tank. I can touch the lines that exit the pump while I turn the key on, I have felt a vibration for a few seconds.

- Was using one of the three factory keys that came with the car. I tried some things to correct the no start.

=Tried the key on (but not all the way to crank) for five to ten seconds, then key off for five to ten seconds and repeated two times and again three times with both the old charged battery and the new battery. No luck with that. Tried all three keys.

=Undid the battery for an hour the first time and for two days later when I waited to get a new battery, no luck with that either.

=Tried locking and unlocking the doors both with all three keys and both remote key fobs. No luck there. NOTE- the key fobs will work the door locks but neither will open the trunk now. Not sure if that is a clue.

- For what it may be worth I had only an ignition key with one of the remote fobs on the key ring. My owner’s manual mentions interference but I was using the same factory key + fob that had started the car about four hours before the no start and for over 18 years before that.

-Tried leaving a key in the ignition for many hours in the off position and also for maybe ten minutes in the on position (dash lights lit up) No luck with that.

-Called a Nissan service manager about this. Will have to have it towed if I want them to check it out. They gave me the number of a local LOCKSMITH who has come by twice. First time he seemed to think the immobilizer system is not at fault. He looked at the little red security on the dash when he cranked the engine and made that opinion. He did not try any equipment the first time. He turned the key on and straight over to crank watching the red security light on the dash. It will stay off if you do it that way.

After some investigating in an online Factory Service Manual, my owner’s manual and on the web. Found that with the key on the red security light is supposed to come on if there is a problem with the IMMU/antitheft system.

- Here is what I observe about that red light when I try some things.

= The red light blinks once about every thirty (30) seconds now. I do not know how often before the trouble started but do think it was much more often. My owner’s manual states this indicator light will blink every three (3) seconds if the ignition is in lock, off or ACC position and this sounds correct about the way it blinked before.

= If I turn the key from off directly to the crank position, as the locksmith did, the red light stays off if it was already off while the engine cranks. (NOTE- this is the only way the locksmith did it.)

= If I turn the key to the on position (dash lights are on but not yet to crank) and wait about five seconds

the indicator red security light comes on and stays on

. If I turn the key further, without turning off, to the crank position the engine cranks and the red indicator light stays on constantly while cranking.

Called the locksmith again telling him about my observation. He came back and observed the same thing. He tried some equipment this time. A device he held near the key in the ignition and a device he plugged into the OBDII port. Apparently he did not get readings expected and maybe if I heard him correctly no readings at all. I have since learned there is a coil which surrounds the key, the IMMU I think, and it gets energized when the key is turned on and reads the chip in the key for a code. I did not know enough at the time to ask but am now guessing he was looking for the coil in the IMMU to give a reading. He left telling me he is not sure what is going on. He suggested the crankshaft position sensor may be at fault.

- Did

two checks

of the crankshaft position sensor. One check with the OBDII reader set it in live data mode at RPM. When I crank the engine over it reads some RPM's 350 RPM's. I think this indicates the crankshaft position sensor is working? I also pulled the crank sensor and checked the ohms. It is within the range of 166 to 204 ohms at 68 degrees F, I found in the Factory Service Manual page EC -1671

- Located and cleaned several grounds.

- Removed and checked spark plugs, distributor cap and rotor. These are not new but all have been replaced in the last 30K miles or so.

- Discovered the ignition coils and cam sensor are part of the distributor. Found some tests in the Nissan factory service manual found online and performed those I could. Did the following.

= from page EC-1617 Cleaned two grounds. Did check power supply test

= from page EC-1617 check for voltage between distributor harness connector terminal 5 and ground. Had voltage.

= from page EC-1904 checked ohms on ignition coil harness connector. Had 0.6 ohms. Manual called for0.8 ohms.

= from page EC-1904 checked secondary terminal on distributor head (secondary coil) showed 14.8K ohms. Manual calls for around 16K ohms.

= from page EC-1904 checked power transistor. Between terminal 2 and 8 got 41.6 K ohms OK

= from page EC-1904 checked distributor cap. Had 6K ohms manual showed 4K to 8K ohms.

- Checked fuses. Pretty sure all fuses are good, not sure about relays, looked at fuseable links.

= starter signal fuse (10 A) has no voltage with key off and no voltage with key on but not to crank.

- Checked NVIS IMMU things I can check

= from page EL-310 NVIS IMMU connector; check power supply circuit. With key off terminal 8 has battery voltage

= from page EL-311 NVIS IMMU connector; check IGN SW. ON signal. Key on =OK

= from page EL-311 NVIS IMMU connector 4 for continuity = OK

My dilemma at this point is the conflict between the NATS codes the car throws and the opinion of the locksmith. I can start to replace parts but understand that if the immobilizer system has cut things off, then this will be pointless.

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