P2804

Code

Generic P — Powertrain

Transmission Range Sensor B Circuit Intermittent

Brand: Generic

Type: P — Powertrain

Views: UK: 14 EN: 77 RU: 30

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Page language: EN

Causes

Damaged, chafed or pinched wiring in the sensor B circuit
Corroded, loose or contaminated connector(s) at the sensor or at the module
Faulty transmission range (gear position) sensor
Water intrusion or debris in connector or sensor
Poor ground or reference voltage to the sensor
Intermittent internal fault in the transmission control module/PCM or damaged PCM pin

Symptoms

Malfunction Indicator Lamp (MIL) illuminated or stored DTCs related to range sensor
Incorrect gear indicator on dash or intermittent loss of gear indication
Transmission stuck in limp/limitation mode or defaults to a single gear
Starter will not crank when lever in P/N (starter-inhibit symptoms) or intermittent no-start condition
Unexpected shift behavior, shift delays or failure to engage selected gear

What to check

Read and record freeze-frame and pending codes with OBD-II scanner; look for related transmission or CAN bus codes
Visually inspect transmission range sensor connector and wiring for damage, corrosion, pin deformation, or moisture
Wiggle harness and connector while watching live data for range sensor B to reproduce the intermittent fault
Backprobe signal, reference and ground pins at the sensor with a DVOM or lab scope while cycling the shifter through positions
Check for continuity between sensor ground and chassis ground and between sensor reference and PCM reference; check for shorts to battery (+B) and to ground
Inspect and test other nearby circuits for evidence of shorts or damage from rubbing/heat

Signal parameters

Typical reference/supply: ~5.0 V reference from PCM (verify exact value for vehicle)
Signal behavior: circuit B should switch or change state consistently as selector is moved — commonly toggles between near 0 V and near reference voltage or produces a defined digital/pulsed pattern
Intermittent faults show unstable or missing transitions, spikes or brief loss of signal
Expected continuity: harness continuity to PCM pin should be low (near 0 Ω); open circuit or high resistance indicates break
No persistent short to battery (+B) or ground when measured

Diagnostic algorithm

Retrieve and document DTCs, freeze frame and live data. Note vehicle symptoms and when code sets (at key on, during shift, or driving).
Perform a visual inspection of transmission range sensor B connector, wiring harness routing and PCM connector. Look for corrosion, bent pins, heat damage or pinch points.
With ignition ON, backprobe sensor connector: verify presence of reference voltage, sensor ground and observe signal while moving selector through all positions. Use lab scope if available to capture intermittent anomalies.
Perform a wiggle test: move harness and connectors while monitoring live data to try to reproduce the intermittent. If fault reproduces, repair wiring or connector at identified stress point.
Check continuity between sensor signal pin and PCM signal pin with ignition OFF. Check for short to battery and short to ground. Repair any open or shorted sections.
If wiring and connectors test good, swap or bench-test the transmission range sensor (if serviceable) or replace sensor B per manufacturer procedure.

Likely causes

Loose or corroded connector at transmission range sensor
Wiring harness damaged where it flexes or routes near heat/moving parts
Failed range sensor (internal contacts worn or contaminated)
Moisture intrusion causing intermittent shorts/opens
Connector terminal pushed out or bent

Fault status

⚠️ Status

P2804 — Intermittent fault detected on Transmission Range Sensor B circuit. The control module observed unstable or missing signal transitions from the range/gear position sensor (circuit B).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours