B3721 Trouble Code

View B3721 obd/2 error code description and symptoms. B3721 engine photo

HO2S Sensor Circuit Malfunction (HO2S-11) During testing the HO2S Heaters are checked for opens/shorts and excessive current draw.
The test fails when current draw exceeds a calibrated limit and/or an open or short is detected. Short to VPWR in harness or HO2S. Water in harness connector. Open VPWR circuit. Open GND circuit. Low battery voltage. Corrosion or poor mating terminals and wiring Damaged HO2S heater. Damaged PCM.

Circuit High Input codes like B3721 are mostly caused by defective alternators that develop excessive voltages, although there may be other causes as well, such as short circuits that 'leak' current into a particular system from other, unrelated systems that work on higher voltages. Note that in the case of short circuits that leak power into a control circuit, there is likely to be other, seemingly unrelated trouble codes present along with the code(s) being investigated. Diagnosing a 'high input' code will always involve a thorough testing of the charging system as a first step, followed by measures to isolate the system from all other possible sources of power during resistance, continuity, and reference voltage tests.

Difficulty Level (Easy)
Level
Repair Time (45 Min.)
Time
Cost Prediction : $ 80-120

B3721 Error Code Repair Process :

If your transmission transfer case disengaged solenoid short to ground 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 B3721 and engine control unit are in charge of monitoring a bunch of different transmission transfer case disengaged solenoid short to ground, and if they get a reading that's a little out of whack, up pops the check engine light.

Wrench Tool B3721 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.

Common Causes of B3721

A common cause of code B3721 is the failure of Transmission Transfer Case Disengaged Solenoid Short to Ground, but there are several other possible causes as well, such as ;

B3721 code for all cars

You can view according B3721 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+B3721 Dodge Aspen +B3721 Cadillac Model D +B3721 Fairthorpe Zeta +B3721 Abarth Monomille +B3721 Alvis 32hp

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