What Does P0739 Mean?
The TCM has detected that the high-resolution timing reference signal B is producing no pulses. This signal provides detailed crankshaft position data used by the TCM for precise shift timing and torque converter clutch control. Without it, the TCM loses the ability to fine-tune shift events relative to engine firing pulses. The driver may notice slightly rougher shifts and reduced torque converter clutch efficiency.
Common Causes
35%
Failed high-resolution crankshaft/timing reference sensor B with no output
25%
Open circuit in the wiring between the timing reference sensor and the TCM
15%
Damaged or missing teeth on the reluctor ring/tone wheel at the sensor B location
15%
Corroded or disconnected connector at the sensor or TCM preventing signal transmission
10%
TCM input buffer circuit failure for the timing reference B channel
Diagnostic Steps
1
With the engine running, use an oscilloscope to probe the timing reference signal B wire at the TCM connector — you should see a pulsed AC waveform. No signal confirms total signal loss.
2
Measure the resistance across the timing reference sensor B terminals (typical range 200–2000 ohms for magnetic sensors). An open or shorted reading confirms sensor failure.
3
Check continuity of each wire from the sensor connector to the TCM connector. Also check for shorts to ground and shorts to power in the circuit.
4
Inspect the sensor air gap and the reluctor ring/tone wheel for damage, debris, or missing teeth. Clean any metallic contamination from the sensor tip.
5
If the sensor and wiring test normal, verify the signal reaches the TCM input pin by backprobing at the TCM — if the signal is present at the connector but the code persists, the TCM input circuit may be faulty.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The TCM has detected that the high-resolution timing reference signal B is producing no pulses. This signal provides detailed crankshaft position data used by the TCM for precise shift timing and torque converter clutch control. Without it, the TCM loses the ability to fine-tune shift events relativ...
The most common cause of P0739 (Timing Reference High Resolution Signal B No Pulses) is: Failed high-resolution crankshaft/timing reference sensor B with no output
Typical repair costs for P0739 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission will still shift using the primary speed sensors, but shift quality and torque converter clutch operation may be degraded. The vehicle is safe to drive to a repair facility. Shifts may feel slightly rougher than normal.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0739 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Automatic Transmission / Engine Timing Reference
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
