B1681 Code:

OBD-II Diagnostic Body (B) Trouble Code

Possible Cause

Common causes of B1681 is include shorted, open, corroded, or damaged wiring circuits or connectors, faulty shift solenoid/s, defective engine drivability sensors (especially the engine temperature sensor), dirty or contaminated transmission fluid that restricts flow, defective valve body, a faulty PCM. PCM failure is rare.

Common Symptoms

  1. OBD-II equipped vehicles utilize a sophisticated computerized control system that calculates various engine drivability inputs with vehicle speed inputs, engine/turbine speed inputs, and transmission output speed inputs to determine the desired degree of high pressure transmission fluid necessary to achieve maximum fuel efficiency, to optimize engine performance, and provide the greatest engine and transmission longevity
  2. If the resistance level does not decrease with heat and increase as it cools, replace the sensor. If everything has checked out thus far, turn the key to the "ON" position and test for the presence of a voltage (and a ground signal) at the exhaust gas temperature/pressure (or heated oxygen) sensor electrical connector
  3. Some applications are equipped with up to 18 separate control modules. If you choose to tackle this monumental task, begin with a careful visual inspection of all system circuitry, connectors, and fuses
  4. If the fuel shutoff switch and all system circuitry checks out, suspect a defective PCM (or other related controller)

Similar Problems

Auxiliary Emission Controls
TP Sensor Learn Not Complete
Cruise Vehicle Speed/Set Speed Difference Too High

B1681 Troubleshooting

Having one of the signs of a bad gasket is usually not enough to prove a failure of a gasket, but multiple symptoms are most likely the result of gasket failure. It is advisable to have the vehicle driven as little as possible whenever the symptoms occur. Depending on the symptoms, either have the gasket replaced or repaired.
The cost of replacing a gasket usually varies from one mechanic to the other. Replacing a gasket is quite expensive in modern engines due to their location and the amount of labor that is required to replace them. B1681 OBD2 reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.

How to turn off B1681 check engine light ?

There are two ways to turn off the check engine light:

A repair technician can do so once repairs have been made.
The OBD II can automatically turn it off when it fails to detect the problem after several diagnostic cycles.

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