Output Shaft Speed sensor circuit intermittent failure The output shaft speed sensor signal to the PCM is irregular or interrupted.
Harness connector not properly seated Harness intermittently shorted, or open Harness connector damaged OSS sensor damaged, or not installed properly Verify harness and connector integrity Verify OSS sensor proper installation.
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.
When you turn on the ignition, the Service Engine Soon or Check Engine B278A light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If engine overboost condition so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the engine overboost condition.
Difficulty Level (Easy)
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Repair Time (20 Min.)
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Cost Prediction : $ 30-110 |
B278A 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. |
You can view according B278A DTC for your car model. We selected several models to see obd2 solutions click and view it.