Damaged or corroded electrical connector at the turbine speed sensor or TCM; Chafed or broken wiring in the sensor circuit, often near the transmission bell housing or exhaust heat; Failing turbine speed sensor due to heat, debris, or internal electrical breakdown; Intermittent open or short inside the TCM, especially on higher-mileage units; Metal debris or sludge on the sensor tip interfering with the magnetic pickup; Poor ground connection for the TCM or transmission, causing voltage fluctuations

DTC codes / Nissan codes / P1900

P1900 · NissanTurbine Speed Sensor Circuit Intermittent

Q: What does code P1900 mean?

Turbine Speed Sensor Circuit Intermittent. P1900 on Nissan vehicles indicates that the transmission control module (TCM) has detected an intermittent signal from the turbine speed sensor, which monitors the rotational speed of the torque converter turbine inside the automatic transmission. The circuit works but the signal drops out or becomes erratic, so the TCM cannot consistently calculate slip or shift timing.

P1900 on Nissan vehicles indicates that the transmission control module (TCM) has detected an intermittent signal from the turbine speed sensor, which monitors the rotational speed of the torque converter turbine inside the automatic transmission. The circuit works but the signal drops out or becomes erratic, so the TCM cannot consistently calculate slip or shift timing.

SystemPowertrain

Code typeNissan specific

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or transmission warning light, often with no other noticeable symptoms
Harsh or delayed gear shifts, especially when the transmission is cold
The transmission may enter limp mode, holding a single gear and limiting vehicle speed
Slight shudder or hesitation during acceleration as the TCM struggles to adjust line pressure
In rare cases, the engine may stall when coming to a stop if the TCM misjudges converter clutch engagement

Common causes, most likely first

Damaged or corroded electrical connector at the turbine speed sensor or TCM
Chafed or broken wiring in the sensor circuit, often near the transmission bell housing or exhaust heat
Failing turbine speed sensor due to heat, debris, or internal electrical breakdown
Intermittent open or short inside the TCM, especially on higher-mileage units
Metal debris or sludge on the sensor tip interfering with the magnetic pickup
Poor ground connection for the TCM or transmission, causing voltage fluctuations

How to diagnose and fix it

Scan all modules for stored and pending codes, then clear codes and test-drive to confirm P1900 returns
Inspect the turbine speed sensor connector and wiring for corrosion, chafing, or loose pins, and repair as needed
Check the sensor resistance and signal output with a multimeter or oscilloscope while wiggling the harness
Remove the sensor and inspect the tip for metallic debris or damage; clean or replace if contaminated
Verify TCM ground and power supply integrity, including battery terminals and chassis grounds
If the sensor and wiring test good, perform a continuity and short-to-ground test on the signal circuit back to the TCM
Substitute a known-good TCM only after all circuit tests pass, then reprogram if required

Intermittent faults hide in plain sight

A common oversight is replacing the turbine speed sensor without checking the harness near the exhaust manifold, where heat damage causes intermittent opens that only appear when the engine bay is hot.
P1900 often sets alongside P0720 or P0715, and technicians who focus only on the output speed sensor miss the turbine sensor circuit entirely.
The TCM may log P1900 from a single dropout event during a rough road or electrical spike, so a one-time code with no driveability complaint does not automatically mean a failed sensor.
Aftermarket transmission fluid that foams or conducts electricity can interfere with the sensor signal, so fluid condition and type should be verified before condemning hard parts.
On some Nissan models, a weak battery or failing alternator causes voltage dips that the TCM interprets as an intermittent sensor signal, so always check charging system health first.

Can I keep driving with P1900?

You can usually drive with P1900, but avoid heavy acceleration and towing until the fault is repaired because the transmission may shift harshly or enter limp mode without warning. If the vehicle feels sluggish or refuses to shift, stop driving and have it diagnosed to prevent further transmission damage.

Tools that help

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Guidance is general and written for Nissan vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.