What Does It Mean?
This generic powertrain diagnostic trouble code (DTC) generally applies to OBD-II equipped vehicles that have a transmission fluid level sensor. Vehicle makes may include, but are not limited to, GM, Chevrolet, Ford, Dodge, Ram, Toyota, Hyundai, etc. This code is rare.
The Transmission Fluid Level (TFL) sensor is used to illuminate a warning light on the dashboard in case of low fluid level.
When the fluid level is within an acceptable range, the switch is grounded. When the transmission fluid drops below a predetermined level, the switch opens and a “low transmission fluid level” warning appears on the dashboard.
TFL sensors receive a reference voltage from the PCM. The PCM monitors the circuit and when it recognizes that the switch has opened, it activates the low fluid level warning on the instrument cluster.
Code P070B is set when the PCM detects a malfunction in the range or performance of the transmission fluid level sensor. Related codes include P070A, P070C, P070D, P070E, and P070F.
Code Severity and Symptoms
The severity of this transmission code is moderate to severe. In some cases, this code and related codes may indicate a low transmission fluid level which, if left unaddressed, can damage the transmission. It is a good idea to address this code as soon as possible.
Symptoms of a P070B trouble code may include:
Low transmission fluid warning light illuminated
Check engine light illuminated
Transmission performance issues
Common causes of this DTC code
Causes
Possible causes of this code may include:
Faulty transmission fluid level sensor
Low transmission fluid level
Wiring problems
Faulty PCM
Diagnostic and Repair Procedures
Start by checking the transmission fluid level and condition according to the manufacturer’s recommendations. Then, inspect the transmission fluid level sensor and its corresponding wiring. Look for loose connections, damaged wiring, etc. If damage is detected, repair as necessary, clear the code, and see if it returns. Next, check for Technical Service Bulletins (TSBs) related to the issue. If nothing is found, you will need to proceed with step-by-step diagnosis of the system.
The following is a generalized procedure, as tests for this code vary by vehicle. To accurately test the system, you will need to refer to the manufacturer’s diagnostic flowchart.
Check the Wiring
Before continuing, you will want to consult the factory wiring diagrams to determine which wires are which. Autozone offers free online repair manuals for many vehicles and ALLDATA offers single-vehicle subscriptions.
Check the Reference Voltage Side of the Circuit
Ignition on, use a digital multimeter set to DC volts to check the reference voltage (usually 5 or 12 volts) from the PCM. To do this, connect the negative meter lead to ground and the positive meter lead to the sensor B+ terminal on the harness side of the connector. If no reference signal is present, set the meter to ohms (ignition off) between the reference voltage pin on the TFL and the reference voltage pin on the PCM. If the meter reads out of limits (OL), there is an open circuit between the PCM and the sensor that will need to be located and repaired. If the meter reads a numerical value, there is continuity.
If everything is okay up to this point, you will want to verify that the PCM is powered. To do this, turn the ignition on and set the meter to DC volts. Connect the positive multimeter lead to the PCM’s reference voltage terminal and the negative lead to ground. If there is no reference voltage from the PCM, the PCM is likely faulty. However, PCMs rarely fail, so it is a good idea to double-check your work up to this point.
Check the Ground Side of the Circuit
Ignition off, use a digital multimeter set to ohms to check for continuity. Connect the meter between the transmission fluid level sensor’s ground terminal and chassis ground. If the meter reads a numerical value, there is continuity. If the meter reads out of limits (OL), there is an open circuit between the PCM and the sensor that will need to be located and repaired.
Check the Sensor
If everything checks out at this point, the sensor is likely faulty. To check this, turn the ignition off and set your multimeter to read ohms. Remove the connector from the transmission fluid level sensor and connect the meter to the sensor’s terminals. If the meter reads out of limits (OL), the sensor is open internally and must be replaced.