B3981 Lexus Ls 300 OBD Code

OBD/2 B3981 error code description and symptoms.

Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM). If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored.

A good starting point in your diagnosis is checking all system fuses and fusible links. This can be done using the DVOM on the voltage setting. You will want to test the fuses with circuits loaded. Some fuses will appear normal until a load is placed on their respective circuit; at which point they will fail. This has been the cause of many 'phantom malfunctions'. Consult your vehicle information source for fuse and fusible link locations. If all fuses are in working order, you may want to check TCM relay operation by swapping identical relays. Usually the horn relay, starter relay, fuel pump relay, air conditioning clutch relay, and controller relays are similar enough in design to swap for diagnostic purposes.

B3981 Lexus Ls 300 Error Code Repair Process :

If your vehicle failed a B3981 test and the B3981 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 door handle switch circuit short to ground 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 door handle switch circuit short to ground: 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.

Common Causes of Lexus Ls 300 B3981 OBD2 Code

A common cause of code B3981 is the failure of Door Handle Switch Circuit Short To Ground, but there are several other possible causes as well, such as ;

Damaged camshaft position (CMP) sensor
Failures of clutch motion/travel sensors.
Camshaft Position Sensor harness is open or shorted
Air fuel ratio (A/F) Sensor 1 Bank 1 circuit poor electrical connection

B3981 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.

Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.

About Us | Contact | Privacy

B3981 Lexus Ls 300 OBD Code

B3981 Lexus Ls 300 Error Code Repair Process :

Common Causes of Lexus Ls 300 B3981 OBD2 Code

B3981 code for other Lexus cars