What Does P0726 Mean?
The TCM has detected that the engine speed (RPM) input signal is outside its expected range or is not performing correctly relative to other speed sensor inputs. This signal is critical for calculating gear ratios, controlling shift points, and managing torque converter clutch operation. The driver may experience erratic shifting, harsh engagements, or the transmission defaulting to limp mode.
Common Causes
35%
Faulty engine speed sensor (crankshaft position sensor) providing erratic or out-of-range signal
25%
Damaged or corroded wiring between the engine speed sensor and the TCM
20%
Excessive crankshaft endplay or damaged reluctor ring causing inconsistent signal
10%
TCM internal fault in the engine speed input processing circuit
10%
Interference from nearby electromagnetic sources or poor grounding
Diagnostic Steps
1
Compare the engine RPM PID from the ECM to the engine RPM PID from the TCM in live data — they should match closely. A significant discrepancy indicates a signal path issue to the TCM.
2
With the engine running, use an oscilloscope on the engine speed sensor signal wire at the TCM to verify a clean, consistent AC waveform that increases proportionally with RPM. Look for dropouts, noise, or amplitude variations.
3
Inspect the crankshaft position sensor for proper air gap (typically 0.5–1.5mm depending on manufacturer), contamination with metallic debris, or physical damage to the sensor tip.
4
Check the reluctor ring/tone wheel on the crankshaft for missing teeth, cracks, or damage that would cause signal irregularities.
5
Verify all grounds between the engine, transmission, and body are clean and tight — measure voltage drop across grounds (should be less than 0.1V).
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The TCM has detected that the engine speed (RPM) input signal is outside its expected range or is not performing correctly relative to other speed sensor inputs. This signal is critical for calculating gear ratios, controlling shift points, and managing torque converter clutch operation. The driver ...
The most common cause of P0726 (Engine Speed Input Circuit Range/Performance) is: Faulty engine speed sensor (crankshaft position sensor) providing erratic or out-of-range signal
Typical repair costs for P0726 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Erratic shifting can create unexpected acceleration or deceleration. The transmission may default to limp mode, limiting speed. The vehicle can be driven at reduced speed to a repair facility, but avoid highway driving if shifting is unpredictable.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0726 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission / Engine Speed Input
Difficulty
Type
Generic (SAE)
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