B0121 Nissan Altima OBD Code

OBD/2 B0121 error code description and symptoms.

Brake Switch Circuit Input Malfunction Indicates PCM did not receive a brake pedal position (BPP) input. Open or short in BPP circuit Open or short in stoplamp circuits Damaged PCM Malfunction in module(s) connected to BPP circuit. (Rear Electronic Module [REM] Windstar and LS6/LS8 or Lighting Control Module (LCM) Continental and Town Car. Damaged brake switch Misadjusted brake switch Check for proper function of stoplamps.

As long as the throttle plate remains closed, the idling speed and quality is controlled by the PCM via the idle control valve, and as can be seen from the above it should be clear that idle control on a gasoline engine is a complex affair. For instance, if the engine is started in sub-zero temperatures, the PCM will command the idling control valve to allow less air to enter the engine to enrich the air/fuel mixture to create a condition which is roughly analogous to how chokes worked on carburetted engines to control idling in cold weather.

B0121 Nissan Altima Error Code Repair Process :

If your cylinder 10 contribution/balance fault check engine light is illuminated, it's best to take it in for diagnostic testing, which can feel like a hassle. Because while the lights vary in appearance from vehicle to vehicle, all have the same basic meaning: There's a problem with the car's emissions system. The on-board diagnostics system B0121 and engine control unit are in charge of monitoring a bunch of different cylinder 10 contribution/balance fault, and if they get a reading that's a little out of whack, up pops the check engine light.

Common Causes of Nissan Altima B0121 OBD2 Code

A common cause of code B0121 is the failure of Cylinder 10 Contribution/Balance Fault, but there are several other possible causes as well, such as ;

Failures of clutch motion/travel sensors.
Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection
Incorrect Positive Crankcase Ventilation (PCV) hose connection
Dirty Oil

B0121 is a kind of Body Trouble Code

Auto body problems aren't always easy to spot. Diagnosing auto body problems sometimes requires a little know-how. In this section you'll find articles dedicated to teaching you how to diagnose auto body problems.

Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.

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B0121 Nissan Altima OBD Code

B0121 Nissan Altima Error Code Repair Process :

Common Causes of Nissan Altima B0121 OBD2 Code

B0121 code for other Nissan cars