OBD-II trouble code
P0713: Transmission Fluid Temperature Sensor "A" Circuit High Input
Signal voltage is sitting at the reference rail, which means the circuit is open. The fluid reads permanently freezing, and the most likely place for that open is a connector on the transmission case that fluid has quietly crept into.
Quick facts
- System
- Powertrain
- Category
- Transmission
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $1,000
- DIY difficulty
- Advanced DIY
What does P0713 mean?
The module supplies a reference voltage through a resistor and measures what the sensor pulls it down to. Cold fluid means high sensor resistance and a high signal voltage; hot fluid means the opposite. When the signal sits at the full reference value with nothing pulling it down at all, no real temperature explains it, and the module stores this code. The circuit is open — a broken wire, a disconnected or corroded connector, or a sensor element that has failed open.
What you get as a result is the mirror image of the low-input fault. Instead of a transmission convinced it is overheating, you have one convinced the fluid is permanently at winter temperature, and the strategy it runs in response is the cautious cold-fluid one: torque converter lockup withheld, a shift schedule tuned for thick fluid, and on many vehicles top gear simply not offered. Nothing about that feels broken from the driver's seat. It feels like a car that revs a little higher on the motorway than it used to and gets worse fuel economy — which is exactly why this code frequently goes unaddressed for months, sometimes noticed only when someone finally reads the light.
The useful diagnostic insight on this member of the family is where the open tends to be, and it is a failure mode no other temperature sensor circuit in the library shares. The sensor lives in fluid, and the wires leaving it pass out of the transmission through a sealed pass-through connector in the case. That seal is a wear item. Once it hardens, automatic transmission fluid wicks along the conductors and into the connector body, where it does two things: it lifts the terminals apart as it accumulates, and it degrades the plating so the contact resistance climbs until the circuit is effectively open. A connector that looks perfectly seated will be full of fluid when you unclip it. Anyone who has diagnosed this circuit more than a few times checks there before running a single continuity test, because it is both the most likely cause and, sitting outside the transmission, by a wide margin the cheapest to fix.
The second thing worth asking before testing anything is what the vehicle has had done recently. Because this sensor is bundled into the internal harness with the solenoids, it is disturbed by any job that opens the pan — a fluid and filter service, a solenoid replacement, a valve body repair, a rebuild. A connector not fully latched on reassembly presents exactly as an open circuit and does so within a few miles of the vehicle being handed back. A code that appeared immediately after transmission work is far more likely to be an assembly issue than a failed part, and finding that out costs one question.
Common causes
- Open signal or ground wire between the transmission and the control module
- Pass-through connector on the transmission case degraded by fluid wicking into the terminals
- Sensor element failed open, usually within the internal wiring harness
- Connector not fully latched after a fluid service, solenoid replacement or rebuild
- Corroded or spread terminals in the sensor or module connector
- Broken conductor inside the internal transmission harness where it flexes near the valve body
- Poor or open ground shared with other transmission sensors
- Harness damaged during unrelated work near the bellhousing or subframe
- Rodent damage to the external transmission loom
- Control module input circuit failure holding the signal at the reference voltage
Symptoms
- Fluid temperature displayed on a scan tool at an implausibly cold value even after a long drive
- Torque converter clutch never locking up, leaving engine speed high at cruising speed
- Top gear unavailable or the transmission holding lower gears for longer
- Fuel economy down with no other change in how the vehicle behaves
- Shifts that feel soft or late rather than harsh
- Check engine light with P0700 stored alongside
- Symptoms appearing within a few miles of transmission or fluid service work
- Other transmission codes stored at the same time where the shared harness is damaged
- No overheat protection available, with no obvious sign that it is missing
Diagnostic steps
- 1.Read live fluid temperature after a long drive. A value stuck at an extreme cold reading on a thoroughly warm transmission identifies the fault immediately.
- 2.Ask what work the vehicle has had recently. Any job that opened the transmission pan disturbs this connector, and an unlatched connector after a service is a common and free-to-fix cause.
- 3.Unclip the pass-through connector on the transmission case and inspect it for fluid inside the body and for dull or corroded terminals. This is the single most productive check on this code and it sits outside the transmission.
- 4.Bridge the sensor circuit at the pass-through connector and watch the live reading. A value that swings from extreme cold to extreme hot proves the wiring back to the module is intact and places the fault on the transmission side.
- 5.Test the signal wire and the sensor ground for continuity from the module connector to the case connector, flexing the loom while measuring.
- 6.Perform a voltage drop test on the sensor ground rather than a simple continuity check, since a high-resistance ground can present as an open on a low-current circuit.
- 7.Inspect the external loom for rodent damage and for chafe where it passes brackets, mounts and the exhaust.
- 8.Measure sensor resistance directly once accessible. An infinite reading confirms a failed element rather than a wiring fault.
- 9.Check the terminals in the module connector for spread or backed-out pins, particularly on a vehicle where connectors have been disconnected before.
- 10.After repair, verify that fluid temperature climbs in step with coolant temperature through a full warm-up drive and that lockup engages once warm.
Repair cost
$120 – $1,000
This is the member of the family most likely to end cheaply, because the pass-through connector is such a common cause and sits outside the transmission. Cleaning or replacing that connector, or repairing an external wire, is $120 to $400 including diagnosis, and a connector simply not latched after a recent service is often corrected at no charge by the shop that did the work. Where the open is inside, an internal wiring harness with fluid, filter and gasket is $350 to $800, and $700 to $1,000 where the sensor is integrated into a solenoid pack. Diagnosis alone is $90 to $180.
Estimate your repair
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Open the Repair Cost Estimator with transmission fluid temperature sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.