P0708 Gear position (range) sensor signal reads too high

Transmission range sensor circuit high input

Severity not verified — if the car runs badly, have it inspected

We found no source that sets a drive-or-stop rule for P0708. Bulletins say a bad or misadjusted range switch can stop the engine starting in park or neutral, and complaints describe shifting trouble, so we leave the rating open for a technician.

It gets more serious if:

  • Inspect soon: If the engine will not start in park or neutral, the gear display flashes or goes blank, or the transmission shifts hard or will not engage, have it inspected soon.

Source: how we rate severity

P0708 in short

P0708 means the computer sees too high a voltage from the transmission range sensor, the switch that tells it which gear position you chose. Damaged wiring, a bad or misadjusted switch, or worn shift linkage are the usual causes. It can affect starting and shifting, so get it checked.

The transmission range sensor (also called the PRNDL input or neutral safety switch) reports park, reverse, neutral or drive to the transmission and engine computers. When its signal voltage rises above what the computer allows, it stores P0708.

TroubleCodes.net lists damaged or corroded wiring, a worn or defective sensor, and a switch or linkage that is out of adjustment. Hyundai says the same about its range switch: one that is improperly adjusted or not working can set P0705, P0707 and P0708, with the check engine light on and no start in park or neutral.

GM has a bulletin for 2001-2004 Silverado and Sierra trucks that lists P0708 with a blank or flashing gear display and slow or no engagement, and a 2020 preliminary bulletin with diagnostic tips for P0708 on 8- and 10-speed automatics. NHTSA complaints include a 2004 Silverado fixed with a new park/neutral switch.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Worn, defective or misadjusted transmission range sensor or switch

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a defective or incorrectly adjusted range switch among the causes, Hyundai says an improperly adjusted switch can set P0708, and a 2004 Silverado owner reports the park/neutral switch was replaced for P0708.
    What would change this
    Rises if the gear shown on a scan tool does not match the lever position. Falls if the readout follows the lever through every gear.

  2. Damaged, shorted or corroded wiring or connectors

    Common general cause
    Why it ranks here
    TroubleCodes.net lists burnt, shorted, disconnected or corroded wiring and unexpected power on the circuit from rubbing wires or aftermarket installations.
    What would change this
    Rises if the signal circuit shows voltage when it should not, or a wiggle test changes the reading. Falls if the wiring tests clean.

  3. Shift cable or linkage worn or out of adjustment

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists excessive wear or adjustment of control linkages and cables.
    What would change this
    Rises if the lever position and the sensor position do not line up in park or neutral. Falls if the linkage is tight and the switch is correctly aligned.

  4. Transmission or engine computer fault (rare)

    Possible — needs testing
    Why it ranks here
    TroubleCodes.net lists a failing PCM or TCM as rare. GM bulletin 020730011 lists P0708 with several other codes, which could also point to shared circuit faults.
    What would change this
    Rises if wiring and the switch test good and other modules show faults. Falls if a sensor or wiring fault is found.
    How to test the transmission control module (tcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Compare the gear position shown on a scan tool with the lever position as you move through park, reverse, neutral and drive, and note which positions give the wrong reading.

    Low riskTool: scan tool with transmission live data

    • IfThe reading is wrong in some positions

      It meansThe sensor or its adjustment is suspect.

      Go to step 2

    • IfThe reading is right in every position and the code is stored

      It meansThe fault may be intermittent. Check the wiring.

      Go to step 3

  2. Check the shift cable and the range switch alignment against the service procedure, and look for linkage wear.

    Use cautionTool: service manual procedure

    Warning:The vehicle can start or move unexpectedly if the lever, switch or starter circuit is disturbed. Set the parking brake, keep the engine off and follow the procedure for your vehicle.

  3. Inspect the sensor wiring and connector for burnt, rubbed or corroded wires and unexpected voltage on the signal circuit.

    Low riskTool: multimeter

Symptoms

  • Check engine light on some vehicles, but not always
  • Overdrive or transmission light that blinks or flashes
  • Gear display blank or flashing
  • Engine starts in a gear other than park or neutral, or will not start in park or neutral Gets more serious: stop and have it checked.
  • Hard shifting or no engagement Gets more serious: stop and have it checked.

How to fix

  1. With the engine off and the parking brake set, look at the sensor connector and wiring where visible for damage or corrosion.

  2. Ask a dealer whether a bulletin applies to your vehicle for P0708.

Parts and cost context

  • Transmission control module (TCM):Modules are rarely the cause, so test the switch, linkage and wiring first. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2004 · Silverado 2500 HD

    Supported by vehicle data

    An NHTSA complaint on a 2004 Silverado 2500 says P0708 was stored for the park/neutral switch, which was replaced. Owner report only.

  • 2020 · Silverado 1500

    Possible — needs testing

    An NHTSA complaint on a 2020 Silverado 1500 says OnStar retrieved P0708 (range sensor circuit high input) after the truck shifted to 4-wheel drive on its own and the rear wheels locked. The owner also mentions a powertrain software recall repair. Owner report only; no cause was confirmed.

  • 020730011 (chevrolet)Status unverified

    Transmission slow or no engagement, blank or flashing PRNDL with P0708

    2001–2004silverado-1500 · issued · NHTSA 10012151

    Lists P0708 among codes (P0872, P0847, P0875, P1711, P1713, U1000) for slow or no engagement, no start and a blank or flashing PRNDL display. The cache summary does not give the repair. The NHTSA record names "Silverado".

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5722A (chevrolet)Status unverified

    Diagnostic tips for P0708 on 8L and 10L transmissions

    2020tahoe, express, camaro · issued · NHTSA 10181136

    Preliminary information giving diagnostic tips for finding the root cause of P0708 on trucks and cars with 8L45, 8L90, 10L60, 10L80 and 10L90 automatics.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Dodge

  • 2007 · Caliber

    Possible — needs testing

    An NHTSA complaint on a 2007 Caliber reports P0708 after the engine kept running with the key out in park; the owner was told a new transmission would be needed. Owner report only.

Hyundai

  • 1999–2009

    Supported by vehicle data

    Hyundai TSB 09-AT-013 says an improperly adjusted or operating range switch can set P0708 on Accent, Elantra, Sonata and Azera. Whether the bulletin is still current is not verified.

  • TSB-09-AT-013Status unverified

    Range switch codes P0705, P0707 and P0708

    1999–2009accent, elantra, sonata, azera · issued · NHTSA 10030984

    An improperly adjusted or operating range switch can set P0705, P0707 and P0708, with the check engine light on and impossible engine start in P or N. Covers Accent, Elantra and Sonata 1999-2009 and Azera 2005-2009 in the NHTSA record.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0707Transmission range sensor circuit signal too low

    Same system Supported by vehicle data

    Hyundai TSB 09-AT-013 lists P0705, P0707 and P0708 together as range switch codes with the same likely causes, so check all three.

  • P0705Fault in the transmission range sensor circuit (gear selector position input)

    Same system Supported by vehicle data

    Hyundai TSB 09-AT-013 covers P0705, P0707 and P0708 together for an improperly adjusted or operating range switch.

All Transmission codes

P0708 questions

What does P0708 mean?

The transmission range sensor, which tells the computer which gear you selected, is sending too high a signal voltage.

Is P0708 serious?

It can affect starting and shifting. Get it checked if the engine will not start in park, the gear display flashes, or shifting is hard.

Should I replace the neutral safety switch?

Check the switch adjustment and wiring first. A misadjusted switch can set the code, though a 2004 Silverado owner did have the park/neutral switch replaced.

Sources and review

  1. GM bulletin 020730011 (NHTSA 10012151) — General Motors ,
  2. Hyundai TSB 09-AT-013 (NHTSA 10030984) — Hyundai Motor America ,
  3. P0708 - Transmission range (TR) sensor/switch - high input — TroubleCodes.net
  4. NHTSA complaint 10232314: 2004 Chevrolet Silverado 2500 — NHTSA Office of Defects Investigation
  5. NHTSA complaint 11682801: 2020 Chevrolet Silverado 1500 — NHTSA Office of Defects Investigation
  6. NHTSA complaint 10402858: 2007 Dodge Caliber — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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