1992 Nissan Sentra

These are unverified consumer reports filed with NHTSA, shown as submitted.

• 12/10/1994· POWER TRAIN

  REAR AXLE SPLINE FELL OUT. *AW

• 12/09/2011· ELECTRICAL SYSTEMFire

  I BOUGHT THIS CAR FOR MY 17-YEAR-OLD DAUGHTER FOR HER FIRST CAR. IT WAS IN MINT SHAPE WITH ONLY 81,000 MILES AT PURCHASE. ON THE DATE STATED SHE WENT TO START THE CAR TO GO TO WORK. UPON STARTING THE CAR SMOKE IMMEDIATELY CAME FROM UNDER THE HOOD NEAR THE FIREWALL. SHE SHUT THE CAR OFF AND OPENED THE HOOD. THERE WAS A FIRE ON THE DRIVER'S SIDE AND REAR FIREWALL WITH FLAMES AND SMOKE COMING FROM THE ENGINE WIRING HARNESS. SHE SHUT THE HOOD AND CALLED THE FIRE DEPARTMENT. WHEN THE FIRE DEPARTMENT ARRIVED THE CAR WAS STILL ON FIRE AND HAD CONSUMED MOST OF THE ENGINE COMPARTMENT AND HAD SPREAD THROUGH THE FIREWALL AND INTO THE DASH. THE CAR WAS COLD AND HAD NOT BEEN RUN SINCE THE PREVIOUS DAY. AFTER DOING SOME RESEARCH AFTER THE FIRE ESPECIALLY WITH REPORTS FROM THE NHTSA THERE MUST BE A DEFECT WITH THE WIRING HARNESS WITH THE SENTRAS. HAS THE NHTSA INVESTIGATED THESE CLAIMS BY OTHER PEOPLE OF SENTRA'S OF THE SAME YEAR SAME COMPONENT CATCHING FIRE? WHILE NO ONE WAS HURT IN THIS FIRE I CAN SEE HOW THIS COULD HAVE BEEN DEVASTATING. THE CAR WAS PARKED VERY CLOSE TO MY HOUSE AND COULD EASILY HAVE SPREAD TO A STRUCTURE FIRE. PLEASE INVESTIGATE THIS COMPLAINT AS WELL AS ANY OTHER COMPLAINTS FOR THIS MODEL CAR FROM OTHER OWNERS. THERE IS DEFIANTLY SOME SORT OF DEFECT WITH THE WIRING HARNESS ON THE SENTRAS OF THIS YEAR MODEL AND A RECALL SHOULD HAVE' ALREADY BEEN CALLED AFTER READING ALL THE COMPLAINTS TO THE NHTSA. *TR

• 12/09/1999· POWER TRAIN,VEHICLE SPEED CONTROL

  WITHOUT WARNING THE 5TH GEAR "POPS"OUT OF GEAR AND INTO NEUTRAL, CAUSING THE ENGINE TO REV. THIS FIRST HAPPENED TO ME WHEN I WAS TRAVELING AT APPROXIMTELY 60 M.P.H., WITH THE CRUISE CONTROL ENGAGED. *AK

• 12/09/1994· POWER TRAIN

  BOOTS TO CV JOINTS FELL OFF.

• 12/08/1995· SERVICE BRAKES, HYDRAULIC

  THE PADS REPLACED THREE TIMES BRAKE ARE MAKING NOISE AGAIN . TT

• 12/03/1998· POWER TRAIN

  TRANSMISSION FAILED RESULTING IN STICKING IN THIRD GEAR.

• 11/14/1999· ELECTRICAL SYSTEMFire

  THIS WIRING HARNESS APPEARED FAULTY FROM THE FACTORY, AND IT TOOK 44000 MILES FOR IT TO RUB THROUGH AND SHORT OUT THE WIRING, CAUSING THE FIRE AND ENGINE STOPPAGE. *AK

• 11/08/1999· POWER TRAIN

  THE TRANSMISSION WON'T UPSHIFT FROM 1ST TO 2ND.

• 11/02/1998· SEAT BELTSCrash

  WHILE DRIVING A DEER JUMPED IN FRONT OF VEHICLE, CAUSING THE VEHICLE TO HIT THE DEER. SEAT BELT DID LOCK NOR RETRACT. ALSO FRONT DRIVER SEAT BELT WILL NOT RETRACT PROPERLY. DEALER/MANUFACTURER. WERE NOT NOTIFIED.

• 10/27/1998· ENGINE AND ENGINE COOLINGFire

  VEHICLE ENGINE FIRE.

• 10/24/2002· STEERING

  INDEX AND MIDDLE FINGERS BENT AND TWISTED TOWARDS THE BABY FINGERS. SEE PHOTOS AT: HTTP://PHOTOS.YAHOO.COM/MIKETOMICH THIS INFORMATION BEING SUBMITTED ON BEHALF OF JOHN REED BY MIKE TOMICH 989, 665-2311 DT

• 10/14/2003· SERVICE BRAKES, HYDRAULIC

  BRAKES LOCK IN EMERGENCY AND NORMAL BRAKING, CAUSING SKIDS, 3 NEAR-MISSES OVER THE LAST WEEK. *LA

• 10/13/1995· SEAT BELTS

  DRIVER/PASS FRONT SHOULDER/LAP BELT WON'T RETRACT INTO DOOR ASSEMBLY. TT

• 10/03/2000· POWER TRAIN,VISIBILITY

  #1: I HAVE A NISSAN SENTRA 92 MODEL WITH AUTOMATIC TRANSMISSION. WHEN I FIRST START TO DRIVE IT WHEN ITS COLD, THE TRANSMISSION RUNS JUST FINE. IT UPSHIFTS NORMALLY AS IT SHOULD ALL THE WAY UP TO OVERDRIVE (4TH GEAR) FOR NORMAL HIGHWAY SPEED. HOWEVER, AFTER IVE DRIVEN IT FOR ABOUT 30 MINUTES IN STOP-&-GO TRAFFIC OR WHEN IT HAS BEEN DRIVEN AT HIGHWAY SPEEDS (40-65 MPH) & MADE SEVERAL STOPS IN TRAFFIC (I.E.: IT HAS WARMED-UP) THE TRANSMISSION WOULD FAIL TO UPSHIFT ABOVE THE 3RD & 4TH GEAR (OVERDRIVE). I WOULD HAVE TO REV THE ENGINE RPM UP TO AROUND 4,000 RPM TO ACCELERATE THE CAR TO ABOUT 40 MPH AND CONTINUE TO REV IT UP TO 5,000-6,000 RPM TO ACCELERATE IT FURTHER TO 45-60 MPH. I KNOW THIS IS NOT NORMAL FOR THIS CAR BECAUSE THE ENGINE HAS NEVER RUN THAT HIGH BEFORE TO REACH THOSE SPEEDS. I'VE ALWAYS DRIVEN THIS CAR WITH OVERDRIVE ENGAGED & I'VE NEVER TOWED ANYTHING WITH IT EVER. #2:  FRONT PASSENGER SIDE POWER WINDOW PLASTIC ASSEMBLY WHERE THE CABLE ATTACHES TO THE REGULATOR BROKE. *AK

• 09/29/2011· ENGINE AND ENGINE COOLING

  TL* THE CONTACT OWNS A 1992 NISSAN SENTRA. THE CONTACT STATED THAT WHILE DRIVING, THE VEHICLE EMITTED AN ODOR THAT MADE HIM DIZZY. THE CONTACT ALSO STATED THAT A DOCTOR CONFIRMED THAT CARBON MONOXIDE WAS INHALED DURING THE FAILURE. THE VEHICLE WAS TAKEN TO AN AUTHORIZED DEALER AND THE MANUFACTURER WAS NOTIFIED. THE VEHICLE WAS NOT REPAIRED. THE FAILURE MILEAGE WAS 155,000 AND THE CURRENT MILEAGE WAS 160,000.

• 09/14/2000· SERVICE BRAKES, AIR

  ANTILOCK BRAKES ON 1992 SENTRA SER WITH ORIGINAL DUNLOP TIRES COMPLETELY SHUT DOWN WHEN APPLIED IN EVEN WET CONDITIONS. BRAKES WILL NOT RE-ENGAGE EVEN WHEN TRANSITIONING ONTO DRY PAVEMENT UNLESS THEN ARE TOTALLY RELEASED AND REAPPLIED. THERE IS NO BRAKING ACTION WHEN THESE DEFECTIVE ANTILOCK BRAKES ENGAGE!

• 09/13/2000· ELECTRICAL SYSTEMFire

  ON 6/12/2000, WHILE MY WIFE WAS DRIVING OUR 1992 NISSAN SENTRA OUT OF HER COMPANY'S PARKING LOT, AT 5 MPH, AN ODOR STARTED COMING INTO THE CAR THROUGH ITS AIR VENT. ONE MINUTE LATER, SMOKE STARTED COMING FROM UNDER THE LEFT SIDE OF THE HOOD. WITHIN 3 MINUTES, SHE VERY QUICKLY DROVE BACK TO HER OFFICE, RAISED THE CAR'S HOOD, AND FOUND THE IGNITION WIRING ON FIRE. SHE DUMPED WATER ON THE FIRE AND PUT IT OUT. SHE THEN CALLED THE FIRE DEPT. TO COME AND MAKE SURE THE FIRE WAS OUT. THE FIRE DEPT. AND POLICE BOTH SHOWED UP. THEY INSTRUCTED HER TO HAVE THE CAR TOWED TO OUR AUTO REPAIR SHOP, AND NOT TO TURN ON THE IGNITION SWITCH. WE DID AS THEY INSTRUCTED. I CAME TO HER OFFICE AND WAITED FOR THE TOW TRUCK TO ARRIVE. OUR MECHANIC SAID THAT THERE WAS NO OUTSIDE CAUSE FOR THE WIRING TO CATCH FIRE. NOTHING WAS TOUCHING THE WIRING, NO WIRES WERE EXPOSED, THE WIRING BUNDLE WAS NOT RUBBING UP AGAINST ANYTHING, AND THE WIRING WAS IN ITS ORIGINAL WRAPPED, BUNDLED LOOM. HE SAID THAT THERE WAS NO OTHER CAUSE FOR THIS FIRE EXCEPT THE IGNITION RESISTOR CAPACITOR WAS DEFECTIVE FROM THE FACTORY, AND THAT IT FAILED, GOT HOT, AND BURST INTO FLAMES. HE TOLD ME TO REPORT THIS INCIDENT TO NHTSA AS A DEFECT IN THIS CAR'S WIRING SYSTEM. (I BOUGHT THIS CAR NEW, HAVE NEVER HAD ANY WORK DONE ON ANY WIRING, NOR THE IGNITION SYSTEM, EXCEPT TUNE-UPS. THE LAST TUNE-UP WAS DONE ON 12/15/1999, AND THE ONLY THING DONE WAS NEW SPARK PLUGS, NEW DISTRIBUTOR CAP & ROTOR, AND NEW PCV VALVE INSTALLED. THE WIRING HAS NEVER BEEN TOUCHED, AND HAD NO LOGICAL REASON TO BURST INTO FLAMES EXCEPT FOR A FACTORY DEFECT IN THE WIRING IGNITION RESISTOR CAPACITOR, AS MY MECHANIC HAS STATED, IN A LETTER TO NISSAN MOTOR CORP., P.O. BOX 191, GARDENA, CA., 90248.) NISSAN HAS AGREED TO PAY HALF OF MY REPAIR COSTS, SINCE MY CAR'S 3-YR WARRANTY HAS EXPIRED. THEY SHOULD PAY THE WHOLE COST, BECAUSE THIS PART SHOULD'VE NEVER FAILED. I FILED A FIRE REPORT WITH THEM, FILE NO. CA3175439. *AK

• 09/13/1998· VISIBILITY

  DRIVER AND FRONT PASSENGER DOOR WINDOWS ROLL UP WITH EXTREME DIFFICULTY.

• 09/12/1995· SEAT BELTSCrash

  SEAT BELT DID NOT RESTRAIN DRIVER AND AIR BAG DID NOT DEPLOY DURING HEAD ON COLLISION. TT

• 09/07/2000· TIRESCrash

  INITIALLY, I THOUGHT THIS WAS AN ISOLATED INCIDENT. BUT EVER SINCE THE INVESTIGATION INTO BRIDGESTONE/FIRESTONE BEGAN, I HAVE BEEN THINKING ABOUT WHAT *COULD* HAVE HAPPENED TO MY WIFE. SHE WAS DRIVING THE CAR THE DAY THE TIRE SEPARATED, AND FORTUNATELY, IT WAS NOT ON THE FRONT AXLE. MY BELIEF NOW, IN LIGHT OF THIS RECENT DEVELOPMENT, IS THAT THEY HAVE BEEN HIDING INFORMATION FOR QUITE A LONG TIME.( DOT NUMBER: TIRE SIZE: 17570R13 )

• 08/27/2012· UNKNOWN OR OTHERFire

  AFTER PARKING THE CAR FOLLOWING A BRIEF ERRAND, THE CAR CAUGHT FIRE FOR NO APPARENT REASON. ALTHOUGH IT WAS 20 YEARS OLD, IT WAS IN GOOD CONDITION. THE ENTIRE FRONT OF THE CAR BURNED, IT WAS TOTALED. IT TOOK THE FIRE DEPARTMENT ABOUT HALF AN HOUR FOR THE FIRE TO BE EXTINGUISHED.

• 08/23/1996· SERVICE BRAKES, HYDRAULIC

  ANTILOCK BRAKES FAILED.

• 08/10/2000· ELECTRICAL SYSTEMFire

  ON 6/12/2000, WHILE MY WIFE WAS DRIVING OUR 1992 NISSAN SENTRA OUT OF HER COMPANY'S PARKING LOT, AT 5 MPH, AN ODOR STARTED COMING INTO THE CAR THROUGH ITS AIR VENT. ONE MINUTE LATER, SMOKE STARTED COMING FROM UNDER THE LEFT SIDE OF THE HOOD. WITHIN 3 MINUTES, SHE VERY QUICKLY DROVE BACK TO HER OFFICE, RAISED THE CAR'S HOOD, AND FOUND THE IGNITION WIRING ON FIRE. SHE DUMPED WATER ON THE FIRE AND PUT IT OUT. SHE THEN CALLED THE FIRE DEPT. TO COME AND MAKE SURE THE FIRE WAS OUT. THE FIRE DEPT. AND POLICE BOTH SHOWED UP. THEY INSTRUCTED HER TO HAVE THE CAR TOWED TO OUR AUTO REPAIR SHOP, AND NOT TO TURN ON THE IGNITION SWITCH. WE DID AS THEY INSTRUCTED. I CAME TO HER OFFICE AND WAITED FOR THE TOW TRUCK TO ARRIVE. OUR MECHANIC SAID THAT THERE WAS NO OUTSIDE CAUSE FOR THE WIRING TO CATCH FIRE. NOTHING WAS TOUCHING THE WIRING, NO WIRES WERE EXPOSED, THE WIRING BUNDLE WAS NOT RUBBING UP AGAINST ANYTHING, AND THE WIRING WAS IN ITS ORIGINAL WRAPPED, BUNDLED LOOM. HE SAID THAT THERE WAS NO OTHER CAUSE FOR THIS FIRE EXCEPT THE IGNITION RESISTOR CAPACITOR WAS DEFECTIVE FROM THE FACTORY, AND THAT IT FAILED, GOT HOT, AND BURST INTO FLAMES. HE TOLD ME TO REPORT THIS CAR FIRE TO NHTSA AS A DEFECT IN THIS CAR'S WIRING SYSTEM. (I BOUGHT THIS CAR NEW, HAVE NEVER HAD ANY WORK DONE ON ANY WIRING, NOR THE IGNITION SYSTEM, EXCEPT TUNE-UPS. THE LAST TUNE-UP WAS DONE ON 12/15/1999, AND THE ONLY THING DONE WAS NEW SPARK PLUGS, NEW DISTRIBUTOR CAP & ROTOR, AND NEW PCV VALVE INSTALLED. THE WIRING HAS NEVER BEEN TOUCHED, AND HAD NO LOGICAL REASON TO BURST INTO FLAMES, EXCEPT FOR A FACTORY DEFECT IN THE WIRING IGNITION RESISTOR CAPACITOR, AS MY MECHANIC HAS STATED, IN A LETTER TO NISSAN MOTOR CORP., P.O. BOX 191, GARDENA, CA., 90248.) NISSAN HAS AGREED TO PAY HALF OF MY REPAIR COSTS, SINCE MY CAR'S 3-YR WARRANTY HAS EXPIRED. THEY SHOULD PAY THE WHOLE COST, BECAUSE THIS PART SHOULD'VE NEVER FAILED. I FILED A FIRE REPORT WITH THEM, FILE NO. CA3175439. *AK

• 08/06/1998· POWER TRAIN

  TRANSMISSION LURCHES FORWARD WHEN SHIFTERD FROM 1ST TO 2ND GEAR. (QCAW)

• 08/04/1998· POWER TRAIN

  WHILE DRIVING TRANSMISSIOM POPS OUT OF FIFTH GEAR WHILE APPLYING GAS. THIS IS A MANUAL TRANSMISSION. *AK

• 07/29/1998· EXTERIOR LIGHTING

  HEADLAMP ENCLOSURES ACCUMULATE CONDENSATION.

• 07/26/1995· ENGINE AND ENGINE COOLING

  ENGINE LOCKED UP. *AK

• 07/16/2000· SEAT BELTS

  THE MOTORBELT FAILED ON BOTH PASSENGER AND DRIVER SIDE. *MJS

• 07/08/1997· POWER TRAIN

  WHILE DRIVING THE VEHICLE ON CRUISE CONTROL OR 5TH GEAR, THE GEAR WILL POP OUT, WHEN THE GEAR POPS OUT THE ENGINE WILL ROAR UP MAKING A NOISE, CONSUMER STATES THAT THEY HAVE CONTACTED THE DEALER, AND THE DEALER SAID THAT THE TRANSMISSION SHOULD BE OVERHAULED, DEALER ALSO TOLD CONSUMER THAT IT WAS OUT OF WARRANTY, THE CONSUMER SAID THAT THEY TOLD HER THAT THEY CAN NOT ADJUST THE LINKAGE ON NISSANS. *AK CONSUMER STATED THE STANDARD 5 SPEED ON VEHICLE SHOULD NOT BE ABLE TO JUMP OUT OF GEAR IF THE TRANSMISSION IS CONSTRUCTED CORRECTLY.*JB

• 07/07/1995· ELECTRICAL SYSTEM

  WHILE DRIVING IN A RAIN STORM AND THROUGH STANDING WATER VEHICLE STALLED. *AK

• 07/06/2000· AIR BAGSCrash

  CONSUMER WAS TRAVELING ABOUT 50MPH & ANOTHER CUT THE CONSUMER OFF. CONSUMER RAN ON THE OUTSIDE OF THE EMBANKMENT & RAND HEAD-ON INTO A TREE. UPON IMPACT, AIRBAGS DIDN'T DEPLOY. CONSUMER IS TRYING TO CONTACT THE MANUFACTURER.*AK

• 06/28/2007· ELECTRICAL SYSTEMFire

  PARKED CAR, SMOKE EMERGED FROM HOOD NEAR WIND SCREEN, THEN PAINT BUBBLED IN MIDDLE OF HOOD. SECONDS LATE, ENGINE BURST INTO FLAMES, AND CAR WAS INCINERATED. PRIOR TO THIS, CAR WAS WELL MAINTAINED, HOUSED IN GARAGE, AND HAD JUST PASSED ITS TOUGH NYC ANNUAL INSPECTION. THERE WAS NO SMELL OF GASOLINE PRIOR TO BLAZE, AND NO APPARENT PROBLEM WITH THE CAR. VEHICLE WAS DESTROYED, AND FIRE DEPARTMENT WAS UNABLE TO SAY WHAT CAUSED FIRE. *AK

• 06/22/1998· ENGINE AND ENGINE COOLINGFire

  ENGINE FIRE.

• 06/06/1995· SEAT BELTS

  DRIVERS SEAT BELT NOT MOTORIZED SHOULDER/LAP BELT WILL UNFASTEN WHILE WEARING. PLEASE DESCRIBE DETAILS. TT

• 06/01/1995· ELECTRICAL SYSTEMFire

  ELECTRICAL SHORT, CAUSED FIRE. *SKD

• 05/25/1995· POWER TRAINCrash

  TRANSMISSION MOUNT MADE OF ALUMINUM CASTING FAILED. PLEASE DESCRIBE DETAILS. TT

• 05/22/1995· SEAT BELTS

  TAKATA #522G688; FALSE WARNING INDICATION FROM DASH BOARD, BUCKLE WILL UNLATCH AND RETRACTOR FAILS. PLEASE DESCRIBE DETAILS. TT

• 05/18/1995· SEAT BELTS

  THE FRONT PASSENGER AND DRIVER SIDE SEAT WHEN DRIVING THE SEAT BELT WILL LOCK AND SOME TIME IT LOCK UP ON THE TRACK DEALER REPAIR THIS PROBLEM SIX TIME. TT

• 05/12/1995· SEATS

  PASSENGER AND DRIVER HEAD REST ARE BROKEN. TT

• 05/08/1996· ELECTRICAL SYSTEM

  UPON STARTING, NOTICED SMOKE COMING FROM UNDER HOOD, FOUND FRONT WIRING HAD BURNT APART, FOR NO APPARENT REASON. *AK

• 04/24/1999· ENGINE AND ENGINE COOLING

  WHEN WARMING UP IN THE MORNING IT CUTS OUT AND I WOULD HAVE TO PUMP IT SEVERAL TIMES TO GET IT RUNNING. I WAS AT A BUSY INTERSECTION AND I STEPPED ON THE ACCELERATOR AND IT DIED ALMOST IN THE MIDDLE OF THE INTERSECTION. THIS HAPPEN TO MY WIFE ALSO.*AK

• 04/24/1995· ELECTRICAL SYSTEMFire

  ENGINE COMPARTMENT FIRE, UNKNOWN ORIGIN. TT

• 04/21/1995· ELECTRICAL SYSTEMFire

  WHILE PUMPING GAS, VEHICLE ENGINE CAUGHT FIRE, FIRE DEPT. SUSPECT ELECTRICAL SHORT AS CULPRIT. TT

• 04/13/1995· SEAT BELTS

  THE PASSENGER AND DRIVER SIDE SEAT BELT RETRACTOR SOMETIME LOCK UP . TT

• 04/11/1996· ELECTRICAL SYSTEMFire

  ENGINE COMPARTMENT FIRE, THE ELECTRICAL WIRING FIRE AROUND THE VEHICLE BATTERY SHORTED OUT. *AK

• 04/06/2000· UNKNOWN OR OTHER

  PAINT IS FADING,WAS INFORMED THAT THE MANUFAUTER USED BAD PRIMER, THE PROBLEM IS CALLED DELAMINATION. WAS ALSO INFORMED THE GM HAS REPAINTED CARS BUT NISSAN ISSUED NO SUCH RECALL. AS IT STANDS RIGHT NOW, I HAVE NO TRADE IN VALUE FOR MY CAR WHICH SHOULD. NO SAFETY DEFECT INDICATED IN SUMMARY. *AK

• 03/29/1996· SEATS

  DRIVER SIDE SEATBACK BOLTS ON THE RIGHT STRIP, CAUSING THE SEAT TO FALL BACKWARDS WHILE DRIVING. *AK

• 03/13/2000· ENGINE AND ENGINE COOLING

  WHILE DRIVING ON ROAD AND MAKING A SHARP TURN OR SLOWING DOWN, VEHICLE WILL JUST CUT OFF, OR MAKE A LOUD KNOCKING NOISE WHEN ACCELERATING, THEN SOUND STOPS. IF SITTING AT A RED LIGHT OR AT STOP SIGN, IT VIBRATES VERY BADLY. TOOK IT TO A LOCAL MECHANIC. . DEALER WAS TOLD THAT VEHICLE HAS A BAD INJECTOR INSIDE THE THIRD CYLINDER. *AK

• 03/06/1995· SERVICE BRAKES, HYDRAULIC

  REAR BRAKE FAILURE.

• 02/21/1999· STRUCTURE

  SUBSTANTIAL AMOUNT OF WATER FOUND IN TRUNK. NO LEAKS ARE APPARENT. THERE ARE OPENINGS THAT THE REAR SEATBELTS GO THROUGH. THROUGH THESE OPENINGS A TRAIL OF WATER/DIRT ARE APPARENT. IT SEEMS THAT THE WATER IS GETTING IN THROUGH THIS AREA. WHETHER IT IS COMING DOWN THROUGH THE REAR WINDOW SEAL OR UP FROM BELOW IS INDETERMINABLE BY ME. THE PLUGS HAVE BEEN REMOVED FROM THE BOTTOM OF THE TRUNK TO RELEASE THE WATER, BUT THIS IS NOT A CORRECTION OF THE PROBLEM ONLY A TEMPORARY SOLUTION. *AK