P0700 Transmission module requests the check engine light

Transmission control system fault (TCM requested MIL)

P0700 in short

P0700 means the transmission control module found a fault and asked the engine computer to turn on the check engine light. The real problem is a second code stored in the transmission module. Have it inspected soon, and stop driving if a transmission over-temperature warning tells you to stop.

Many cars have a separate transmission control module (TCM). It cannot light the check engine light directly, so when it stores a fault it sends a request to the engine computer. The engine computer lights the lamp and stores P0700.

P0700 on its own does not tell you what is wrong. A scan tool that can read the transmission module will show the actual fault code. Basic code readers often see only P0700.

Regulations treat the TCM as an emissions-critical module and require the light when the transmission goes into a limp-home mode.

Most likely causes

  1. A specific transmission fault stored in the TCM

    Common general cause
    Why it ranks here
    By definition, P0700 is the TCM asking for the light because it has its own code, so reading that code is always the first step.
    What would change this
    Confirmed when a TCM-capable scan tool shows a stored transmission code.
    How to test the transmission control module (tcm)

  2. Shift adaptation needing a relearn (some low-mileage GM vehicles)

    Supported by vehicle data
    Why it ranks here
    GM bulletin 23-NA-210 says that on some vehicles with 5,000 miles or less, P0700 with P18AE is cleared by a key-cycle and shift relearn.
    What would change this
    Rises if the vehicle is covered and the code stays away after the relearn.
    How to test the transmission control module (tcm)

  3. Valve body fault (some GM vehicles)

    Supported by vehicle data
    Why it ranks here
    In the same GM bulletin, the valve body is replaced only if P18AE returns after the relearn.
    What would change this
    Rises if P18AE comes back after the relearn.

  4. Transmission overheating and self-protection

    Possible — needs testing
    Why it ranks here
    Some transmissions protect themselves when hot and warn the driver. Hyundai's DCT warnings describe this, but that page does not name the model.
    What would change this
    Rises if a transmission temperature warning appeared, especially in stop-and-go traffic or on hills.

What to test first

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

  1. Note any warning message on the dash and how the car shifts, before the codes are cleared.

    Low risk

  2. Read codes from the transmission control module, not just the engine module, using a scan tool that supports it.

    Low riskTool: scan tool that reads the transmission module

  3. Have a GM dealer clear the codes and perform the key-cycle and shift relearn in bulletin 23-NA-210.

    Best left to a shopTool: dealer scan tool

    Warning:Dealer procedure that needs a dealer-level scan tool.

Symptoms

  • Check engine light, often with no other symptom
  • Late, early or firm shifts
  • Transmission stuck in one gear or reduced power (limp-home mode) Gets more serious: stop and have it checked.
  • Transmission temperature warning telling you to stop or park Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. Do not clear the code before the transmission module has been read. The stored code is the real clue.

  2. Have the transmission module codes read with a scan tool that supports it. Basic readers often show only P0700.

  3. If a transmission temperature warning appears, find a safe place to stop and follow the message, for example parking with the engine running.

    Warning:Only stop where it is safe to do so.

Parts and cost context

  • Transmission control module (TCM):Do not replace the module because of P0700 alone. It is usually reporting a fault elsewhere.

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

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2023–2025 · Silverado 1500

    Supported by vehicle data

    GM bulletin 23-NA-210 covers P0700 and/or P18AE in the TCM on vehicles with 5,000 miles or less. Clear the codes and run the relearn; replace the valve body only if P18AE returns. The Cadillac CT4, CT5 and Escalade are also covered. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    NHTSA owner complaints mentioning P0700: 30. That shows what owners reported, not how often a cause sets the code.

  • 23-NA-210Status unverified

    Check engine light with P18AE and/or P0700 set in the TCM on vehicles with 5,000 miles or less

    2023–2025silverado-1500 · issued · rev. Version 2 · NHTSA MC-11008967

    Clear the codes and run the key-cycle and shift relearn. Replace the valve body only if P18AE comes back. The bulletin also covers the 2023–2025 Cadillac CT4, CT5 and Escalade and the GMC Sierra 1500.

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

GMC

  • 2023–2025 · Sierra 1500

    Supported by vehicle data

    Covered by the same GM bulletin (23-NA-210) as the Silverado 1500. The bulletin is on NHTSA, but whether it is still current is not verified, so it is labelled vehicle data rather than confirmed.

    NHTSA owner complaints mentioning P0700: 16. That shows what owners reported, not how often a cause sets the code.

  • 23-NA-210Status unverified

    Check engine light with P18AE and/or P0700 set in the TCM on vehicles with 5,000 miles or less

    2023–2025silverado-1500 · issued · rev. Version 2 · NHTSA MC-11008967

    Clear the codes and run the key-cycle and shift relearn. Replace the valve body only if P18AE comes back. The bulletin also covers the 2023–2025 Cadillac CT4, CT5 and Escalade and the GMC Sierra 1500.

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

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

    Primary / secondary Possible — needs testing

    Likely primary: P0705. P0700 only says the transmission module has stored its own code. P0705, the range sensor circuit code, can be that code; read the transmission module with a scan tool and fix P0705 first.

  • P0717No signal from the transmission input or turbine speed sensor

    Primary / secondary Possible — needs testing

    Likely primary: P0717. P0700 only says the transmission module has stored its own code. P0717, the input or turbine speed sensor code, can be that code; read the transmission module with a scan tool and fix P0717 first.

  • P0720Transmission output shaft speed sensor circuit fault

    Primary / secondary Possible — needs testing

    Likely primary: P0720. P0700 only says the transmission module has stored its own code. P0720, the output shaft speed sensor code, can be that code; read the transmission module with a scan tool and fix P0720 first.

  • P0730Transmission gear ratio does not match the selected gear

    Primary / secondary Possible — needs testing

    Likely primary: P0730. P0700 only says the transmission module has stored its own code. P0730, the general gear ratio code, can be that code; read the transmission module with a scan tool and fix P0730 first.

  • P0741Torque converter clutch not engaging as commanded

    Primary / secondary Possible — needs testing

    Likely primary: P0741. P0700 only says the transmission module has stored its own code. P0741, the torque converter clutch performance code, can be that code; read the transmission module with a scan tool and fix P0741 first.

  • P0746Pressure control solenoid A is not working or stuck off

    Primary / secondary Possible — needs testing

    Likely primary: P0746. P0700 only says the transmission module has stored its own code. P0746, the pressure control solenoid A code, can be that code; read the transmission module with a scan tool and fix P0746 first.

All Transmission codes

P0700 questions

What does P0700 actually mean?

It means the transmission computer has stored a fault and asked the engine computer to turn on the check engine light. The real fault is a separate code in the transmission module.

Why does my code reader show only P0700?

Basic readers usually talk only to the engine computer. You need a scan tool that can read the transmission module to see the actual fault.

Is it safe to drive with P0700?

Get it inspected soon. Toyota tells owners to have the vehicle inspected right away when the light comes on for the transmission system. If a warning tells you to stop because the transmission is hot, stop safely.

Sources and review

  1. Toyota Camry Owner's Manual (OM06291U, 2.5L A25A-FKS / 3.5L 2GR-FKS) — Toyota
  2. DTC P0700 — Saab 9-5 (9650) 2010 Workshop Information System — SaabWISOnline (community rehost of Saab/GM service information)
  3. Cal. Code Regs. Tit. 13, § 1968.2 — Malfunction and Diagnostic System Requirements (OBD II) — California Air Resources Board (via Cornell LII)
  4. DCT warning messages (Hyundai owner's manual web page) — Hyundai Motor Company
  5. GM 23-NA-210: MIL with P18AE and/or P0700 set in the TCM on low-mileage vehicles — General Motors / NHTSA ,
  6. NHTSA ODI consumer complaints flat files — National Highway Traffic Safety Administration (NHTSA), Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
Editorial review
Pending
Technician review
Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error

My Car

Pick your car and code pages will point out notes and bulletins for it. Saved only in this browser.

Fill this in from your VIN

Used once to identify your engine; not stored.