Transmission Range Sensor "B" Circuit Low
P2802 indicates the transmission range sensor B circuit is detecting a low or no voltage signal. This sensor tells the transmission control module which gear position the shifter is in, and a low voltage condition prevents proper gear selection and transmission operation.
What You Might Notice
- Check engine light illuminated
- Erratic or harsh shifting behavior
- Vehicle may start in gear instead of park/neutral only
- Transmission in limp-home mode with reduced power
- Overdrive (O/D) or D4 indicator blinking on dashboard
Most Common Causes
- 1
Transmission Range Sensor failure
The sensor itself has failed internally or become disconnected, preventing voltage signal transmission to the TCM. This is the most common cause of circuit low conditions.
- 2
Wiring harness damage or corrosion
The wiring between the sensor and transmission control module is corroded, damaged, or loose, breaking the voltage signal path. Check connectors for corrosion and wires for breaks.
- 3
Transmission control module (TCM) issue
The TCM itself may have a failed input circuit or internal fault preventing it from reading the sensor voltage signal correctly.
- 4
Connector or pin issues
The sensor connector pins are loose, corroded, or improperly seated, creating a high-resistance connection that prevents voltage from reaching the TCM.
How to Diagnose It
- 1
Check Transmission Range Sensor failure — The sensor itself has failed internally or become disconnected, preventing voltage signal transmission to the TCM. This is the most common cause of circuit low conditions.
- 2
Check Wiring harness damage or corrosion — The wiring between the sensor and transmission control module is corroded, damaged, or loose, breaking the voltage signal path. Check connectors for corrosion and wires for breaks.
- 3
Check Transmission control module (TCM) issue — The TCM itself may have a failed input circuit or internal fault preventing it from reading the sensor voltage signal correctly.
- 4
Check Connector or pin issues — The sensor connector pins are loose, corroded, or improperly seated, creating a high-resistance connection that prevents voltage from reaching the TCM.
How to Fix It
- 1
Replace Transmission Range Sensor B
Remove the failed sensor from the transmission and install a new OEM or quality replacement. This resolves the majority of P2802 codes and restores proper gear position signaling.
- 2
Inspect and repair wiring harness
Visually inspect the sensor wiring harness and connectors for corrosion, damage, or loose connections. Clean corroded connectors with electrical contact cleaner and reseat all connections firmly.
- 3
Check sensor connector and pins
Disconnect the sensor connector and inspect pins for corrosion, bending, or poor contact. Use a multimeter to verify voltage is reaching the sensor, then test sensor output with shifter in different positions.
- 4
Test and replace transmission control module if needed
If sensor replacement and wiring repairs do not resolve the code, have the TCM tested by a transmission specialist or dealership. A failed input circuit in the TCM may require module replacement or reprogramming.
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