OBD-II trouble code
P0705: Transmission Range Sensor "A" Circuit (PRNDL Input)
The module cannot read a valid gear selection from the transmission range sensor. Because the same sensor is what permits cranking, this is the code behind the classic "won't start in Park but starts in Neutral" complaint.
Quick facts
- System
- Powertrain
- Category
- Transmission / Shift Control
- Severity
- High severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $120 – $600
- DIY difficulty
- Intermediate DIY
What does P0705 mean?
The transmission range sensor — also sold as the neutral safety switch, PRNDL switch, MLPS or inhibitor switch depending on the make — reports which gear the driver has selected. It is not a conventional two-wire sensor. On most designs it is a multi-position switch riding on the manual shift shaft where it exits the transmission case, and it encodes the selected range as a combination of several parallel circuits that are pulled to ground or left open. Park might be circuits 1 and 3 grounded, Reverse circuits 2 and 3, and so on.
That encoding is the key to understanding P0705. The module is not looking at a voltage and deciding it is out of range — it is looking at a *pattern* and deciding the pattern is impossible. All circuits open at once, two ranges reported simultaneously, or a combination the lookup table simply does not contain will all set this code. That is why P0705 can appear while the transmission still shifts perfectly: the mechanical linkage is doing its job, the electrical report of it is nonsense.
The consequence that brings most people here is not a shifting problem at all. The same switch is what tells the starter circuit it is safe to crank, and it is what closes the reverse lamp circuit. A vehicle with P0705 very often cranks in Neutral but not in Park, or the other way around, or refuses to crank in any position — which is why this code is treated as a no-start rather than a driveability fault. Expect the transmission to default to a fixed gear or a fail-safe shift pattern as well, because a controller that does not know what range the driver picked will not risk commanding a shift schedule.
Common causes
- Worn or internally failed transmission range sensor / neutral safety switch
- Damaged, chafed or rodent-bitten wiring in the harness running along the transmission case
- Corroded or water-intruded connector at the sensor
- Sensor knocked out of index during a transmission, mount or shift-cable replacement
- Stretched, loose or misadjusted shift cable holding the manual shaft between detents
- Open or high-resistance ground for the range sensor circuit
- Failed transmission control module or PCM input driver (uncommon — verify the sensor and wiring first)
Symptoms
- Engine will not crank in Park, but cranks in Neutral (or vice versa)
- Engine will not crank in any gear selector position
- Gear position indicator on the dash is blank, wrong, or shows all positions lit
- Transmission stays in one gear or uses a harsh fail-safe shift pattern
- Reverse lights do not come on, or stay on in other gears
- Check engine light is on
- Vehicle rolls when the selector says Park (linkage-related cases)
Diagnostic steps
- 1.Confirm the basics first: does the gear the driver selected match what the dash indicator shows, and does it match what the scan tool reports as the transmission range PID? Three-way disagreement narrows the fault immediately.
- 2.Watch the range PID on a scan tool while an assistant moves the selector slowly through every position. Note exactly which position or transition the reading fails on — a fault in only one range points at the sensor, a fault in all of them points at power, ground or the connector.
- 3.Unplug the sensor connector and inspect it for water, green corrosion or spread terminals. This connector lives low on the transmission case and gets hit with road spray year-round.
- 4.Check the ground circuit for the sensor with a voltage-drop test rather than a resistance check — a corroded ground can measure a few ohms and still collapse under load.
- 5.Verify shift cable adjustment. With the selector in Park, the manual shaft should sit fully in its Park detent, not just close to it.
- 6.If the sensor is replaced, index it correctly. Many designs mount on a slotted plate and must be aligned in Neutral against alignment marks or with a special tool before the bolts are tightened.
Repair cost
$120 – $600
The sensor itself is typically $35 to $200. On external designs bolted to the outside of the case it is a 30-to-60-minute job and the total lands around $150 to $350. On designs where the switch is internal to the valve body, the pan and fluid must come out and the total moves toward $400 to $600. Wiring or connector repair alone can be well under $150. Diagnosis is $75 to $150 and is worth paying for here, because a misadjusted cable and a failed sensor produce the same complaint.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with transmission range sensor / neutral safety switch replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.