Technical Description of OBD-II Trouble Code
Range/Performance Issue with Transmission Fluid Level Sensor Circuit
What does that signify?
This particular diagnostic trouble code (DTC) is applicable to vehicles equipped with OBD-II that have a transmission fluid level sensor. Various vehicle makes, including but not limited to GM, Chevrolet, Ford, Dodge, Ram, Toyota, Hyundai, etc., may have this code, although it is uncommon.
The transmission fluid level (TFL) sensor is responsible for activating a warning light on the dashboard when the fluid level is low.
When the fluid level is within an acceptable range, the switch is grounded. However, when the transmission fluid drops below a predetermined level, the switch opens and triggers a “low transmission fluid level” warning on the dashboard.
TFL sensors receive a reference voltage from the PCM. The PCM monitors the circuit and activates the low fluid warning on the instrument cluster when it detects that the switch has opened.
Code P070B is set when the PCM identifies a malfunction in the range or performance of the transmission fluid level sensor. Other related codes include P070A, P070C, P070D, P070E, and P070F.
Code Severity & Symptoms
This transmission code ranges from moderate to severe in terms of severity. In some cases, this code and related codes may indicate a low transmission fluid level, which, if left unattended, can lead to transmission damage. It is advisable to address this code as soon as possible.
Symptoms of a P070B trouble code may include:
Common Causes Of This DTC Code
Possible causes for this code may include:
Diagnostic and Repair Procedures
Begin by checking the transmission fluid level and condition according to the manufacturer’s recommendations. Next, inspect the transmission fluid level sensor and its corresponding wiring. Look for loose connections, damaged wiring, etc. If any damage is found, repair it as necessary, clear the code, and check if it reappears. Next, check for any technical service bulletins (TSBs) related to this issue. If no relevant information is found, proceed with a step-by-step diagnosis of the system.
The following is a general procedure, as testing for this code may vary between vehicles. To accurately test the system, it is recommended to refer to the manufacturer’s diagnostic flow chart.
Check The Wiring
Prior to proceeding, consult the factory wiring diagrams to determine the identification of each wire. Autozone offers free online repair manuals for many vehicles, and ALLDATA offers single vehicle subscriptions.
Check the reference voltage side of the circuit
With the ignition on, use a digital multimeter set to DC volts to check for 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, connect the meter set to ohms (with the 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 sensor that needs to be located and repaired. If the meter reads a numeric value, there is continuity.
If everything is functioning properly up to this point, check that there is power coming out of the PCM. To do this, turn the ignition on and set the meter to DC volts. Connect the positive meter lead to the reference voltage terminal on the PCM and the negative lead to ground. If there is no reference voltage from the PCM, the PCM is likely faulty. However, PCMs rarely go bad, so it is advisable to double-check the previous steps.
Check The Ground Side Of The Circuit
With the ignition off, use a digital multimeter set to ohms to check for continuity. Connect the meter between the transmission fluid level sensor ground terminal and chassis ground. If the meter reads a numeric value, there is continuity. If the meter reads “out of limits” (OL), there is an open circuit between the PCM and sensor that needs to be located and repaired.
Check The Sensor
If everything checks out up to this point, the sensor is likely faulty. To check this, turn the ignition off and set your multimeter to read ohms. Remove the transmission fluid level sensor connector and connect the meter to the sensor terminals. If the meter reads “out of limits” (OL), the sensor is internally open and should be replaced.
