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.
Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code B3391, so consult the manual to locate the brake fluid reservoir. Bear in mind that a low fluid level can set code B3391 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.
If your fuel tank temperature sensor circuit malfunction 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 B3391 and engine control unit are in charge of monitoring a bunch of different fuel tank temperature sensor circuit malfunction, and if they get a reading that's a little out of whack, up pops the check engine light.
Difficulty Level (Soso)
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Repair Time (50 Min.)
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| Cost Prediction : $ 40-75 |
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B3391 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 B3391 DTC for your car model. We selected several models to see obd2 solutions click and view it.
Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.
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