B3781 Trouble Code

View B3781 obd/2 error code description and symptoms. B3781 engine photo

Catalytic converters must be warm before they can work properly. On a cold start the PCM provides a rich mixture to keep the cold engine running.
All that extra fuel goes into the catalytic converter. But the exhaust isn't very hot, because, ah, the engine is pretty cold. GM has employed several strategies to fire up the catalytic converter quicker and reduce cold start emissions. One way is to use a secondary air pump that pumps outside air directly into the catalytic converter.

Circuit High Input codes like B3781 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 : $ 70-220

B3781 Error Code Repair Process :

If your vehicle failed a B3781 test and the B3781 Check Engine Light is NOT on, chances are you have a problem with the OBDII system, a burned out MIL lamp, or a faulty catalytic converter. The converter is essentially an afterburner that cleans up the exhaust after it exits the engine. The OBDII system uses wiper rear motor run relay circuit failure a ownstream oxygen sensor to monitor the efficiency of the converter, and it should detect a drop in converter efficiency if the converter has been contaminated or is failing (ignition misfiring, leaky exhaust valves, and oil burning can all damage the converter). What you want to look wiper rear motor run relay circuit failure: Any conditions that might cause ignition misfire, an overly rich or lean fuel condition, or loss of compression. Use your OBD Express DIY to look at the oxygen sensor outputs, coolant temperature, airflow, calculated engine load, and inlet air temperature.

Wrench Tool B3781 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 B3781

A common cause of code B3781 is the failure of Wiper Rear Motor Run Relay Circuit Failure, but there are several other possible causes as well, such as ;

B3781 code for all cars

You can view according B3781 DTC for your car model. We selected several models to see obd2 solutions click and view it.

+B3781 Mazda Kusabi +B3781 Tvr Sagaris +B3781 Opel Adam +B3781 Chevrolet Volt 2 +B3781 Genesis G80

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