P0989 The transmission computer sees a low voltage on the circuit of one of the transmission fluid pressure switches, labelled E

Transmission fluid pressure switch E circuit low

P0989 in short

P0989 means the transmission computer sees a low signal on the circuit of fluid pressure switch E, one of the switches that report hydraulic pressure inside the automatic transmission. A GM bulletin on 6-speed transmissions covers it among false pressure switch codes. Owners report hard shifting and lost power, so have it checked soon.

Modern automatics use pressure switches or sensors to tell the transmission computer what hydraulic pressure is reaching each clutch. P0989 sets when the circuit for switch E reads lower than expected, which can mean a wiring short to ground, a failed switch, or a computer fault.

GM bulletin 070730015 gives information on checking the transmission fluid pressure (TFP) switches for false codes, including P0989, on 6T70, 6T75, 6L50, 6L80 and 6L90 transmissions. We read only the bulletin summary.

Owner complaints on Saturn Aura, Outlook and Vue and a Chevrolet Impala show P0989 stored with shift solenoid and speed sensor codes and with hard shifting, a stuck first gear or lost power. One owner lists it as "TFP switch 5 circuit low". Repairs ranged from a pressure sensor and solenoid assembly to a full rebuild.

Most likely causes

  1. Pressure switch reading falsely or failing (GM 6-speed automatics)

    Supported by vehicle data
    Why it ranks here
    GM bulletin 070730015 covers a TFP switch check for false DTCs including P0989, and one Saturn Aura owner had an internal pressure sensor and solenoid part replaced with P0989 stored.
    What would change this
    Rises on a GM 6-speed automatic from the listed years. Falls if the switch tests normal.
    How to test the transmission control module (tcm)

  2. Wiring short to ground or connector fault

    Possible — needs testing
    Why it ranks here
    Troublecodes.net lists wiring with a short to ground among the likely causes of a low circuit, but our other sources do not show it for this code.
    What would change this
    Rises if the harness shows damage or a bulletin check finds no switch fault. Falls if wiring tests normal.

  3. Internal transmission wear with other shift codes

    Possible — needs testing
    Why it ranks here
    Complaints show P0989 stored with P0752, P0877 and P0700 and followed by a rebuild or a failed wave plate, but the link is the owners and shops, not a bulletin.
    What would change this
    Rises when shift codes and hard shifting appear with the code. Falls if the switch or wiring fix clears it.

What to test first

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

  1. Read all stored codes and freeze-frame data with a scan tool and note every dashboard message. Do not open or unplug anything.

    Low riskTool: OBD-II scan tool

    • IfP0989 is stored with shift solenoid or speed sensor codes and hard shifting

      It meansThe transmission needs a proper diagnosis.

      Go to step 2

    • IfIt is stored alone with normal shifting

      It meansA false code from the pressure switch is possible.

      Go to step 2

  2. Give the VIN to a dealer and ask for open bulletins and recalls on the transmission pressure switches and any special coverage for the transmission.

    Low riskTool: VIN lookup at a dealer

  3. Have a transmission technician check the fluid level and condition, test the pressure switch circuit, and read live data using the maker service information.

    Best left to a shopTool: factory scan tool and pressure gauge

    Warning:Do not drive on if the transmission will not shift out of first gear or drops power; the transmission can overheat, and the car can lose power in traffic.

Symptoms

  • Check engine light
  • Harsh or late shifting
  • Stuck in first gear or lost power Gets more serious: stop and have it checked.

How to fix

Parts and cost context

  • Transmission fluid pressure switch or internal pressure sensor assembly:Check the GM bulletin and any special transmission coverage for your VIN before paying. Labor 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

Saturn

  • 070730015 (saturn)Status unverified

    TFP switch check for false DTCs including P0989

    2007aura, outlook · issued · NHTSA 10021845

    Information on the pressure switch check on 6-speed automatics.

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

Buick

  • 070730015 (buick)Status unverified

    TFP switch check for false DTCs including P0989

    2008enclave · issued · NHTSA 10021845

    Same bulletin as the Saturn entry.

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

Cadillac

  • 070730015 (cadillac)Status unverified

    TFP switch check for false DTCs including P0989

    2007srx · issued · NHTSA 10021845

    Same bulletin as the Saturn entry.

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

Chevrolet

  • P0752Shift solenoid A stuck on

    Shares causes Supported by vehicle data

    Complaints on Saturn Outlook and Vue store P0989 with P0752 (shift solenoid) on the same transmission failure.

  • P0700Transmission module requests the check engine light

    Same system Supported by vehicle data

    P0700 (transmission control system) was stored alongside P0989 in three complaints.

All Transmission codes

P0989 questions

Is it safe to drive with P0989?

Only to get it checked, and only if it shifts normally. If it sticks in first gear or loses power, stop somewhere safe and arrange a tow.

Could P0989 be a false code?

Possibly. A GM bulletin covers a check of the pressure switches for false codes including P0989 on some 6-speed automatics, so ask a dealer to check the VIN.

Sources and review

  1. 070730015: TFP switch check for false DTCs on 6-speed automatics — General Motors ,
  2. NHTSA complaint ODI 10566075: 2007 Saturn Aura — NHTSA Office of Defects Investigation
  3. P0989 Transmission fluid pressure (TFP) sensor / switch E circuit low — Troublecodes.net
  4. NHTSA complaint ODI 10927817: 2008 Saturn Vue — NHTSA Office of Defects Investigation
  5. NHTSA complaint ODI 10543119: 2007 Saturn Outlook — NHTSA Office of Defects Investigation
  6. NHTSA complaint ODI 11246315: 2013 Chevrolet Impala — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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