- Vehicles
- Cars
P0700
P0700 (generic OBD-II): transmission control system MIL request
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
P0700 only means the transmission computer stored its own code and asked for the engine light. Note how the gearbox shifts and ask for the transmission module memory to be read, not just the engine computer.
Safety first
Stop and check this first
- If the gearbox stays in one gear, acceleration and speed are reduced; avoid motorways and overtaking until it is checked.
Safe checks you can perform
- How the gearbox shifts
- What a generic reader sees
- Bulletins for your VIN
Leave these tasks to a qualified professional
- Do not attempt this professional task: Transmission module reading
- Do not attempt this professional task: Communication and connector check
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Transmission module reading
What they doThe technician reads the transmission module memory with diagnostic equipment and follows the procedure for the code found there.
They must show youthe transmission module code list.
In writingthe actual gearbox code and the repair applied for it.
Communication and connector check
What they doIf there are communication codes, the technician inspects the gearbox connector terminals, wiring and corrosion following the manufacturer's procedure.
They must show youphotos of the connector and the terminals inspected.
In writingwhich terminal or wire was repaired.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
How the gearbox shifts
- Who:
- you, driving normally.
- How:
- notice whether the gearbox shifts harshly, stays in one gear, will not engage park or shows a transmission warning on the cluster.
- Result that matters:
- which gearbox symptom comes with the light.
- If the gearbox stays in one gear or will not shift:
- drive gently to the workshop and avoid long trips.
- If the gearbox shifts normally:
- note the code and ask for the transmission module to be read.
- Evidence to keep:
- a note of the symptom, a photo of any cluster warning and the date.
Do not open or handle the gearbox or its connector; that is workshop work.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100 · Stellantis STAR case S2321000006 DTC P0700 Transmission Control System (MIL Request)
What a generic reader sees
- Who:
- you, with a generic OBD-II reader.
- How:
- read the codes and save the freeze frame; bear in mind that many generic readers only read the engine computer.
- Result that matters:
- whether other codes appear besides P0700, especially U communication codes.
- If U codes appear:
- tell the workshop; GM links them to communication connectors or wiring.
- If only P0700 appears:
- you need equipment that reads the transmission module to know the real fault.
- Evidence to keep:
- a photo of the code list.
Plug in and read the tool with the car parked somewhere safe, never while driving. Do not clear the codes: clearing them also erases the freeze frame data the workshop needs.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100 · Title 13, California Code Regulations, Section 1968.2, Malfunction and Diagnostic System Requirements (OBD II)
Bulletins for your VIN
- Who:
- you, asking the authorised service.
- How:
- give your VIN and the codes and ask whether there is a service bulletin or transmission software update for your model.
- Result that matters:
- whether a bulletin matches your model and codes.
- If there is one:
- the workshop should apply it before replacing gearbox parts.
- If there is none:
- the workshop should follow the diagnosis for the code stored in the transmission.
- Evidence to keep:
- the bulletin number or the answer that there is none, with the date.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100 · Stellantis STAR case S2321000006 DTC P0700 Transmission Control System (MIL Request)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- OBD-II genérico
- Product type
- Cars
Known code variants
- P0700
- P0700 caja de cambios
- P0700 OBD2
- P0700 transmission control system
What it means
P0700 is the generic code for transmission control system MIL request. The engine computer stores it when the transmission module detects a fault of its own and asks for the light to come on. GM defines it as MIL illumination requested by the transmission control module, and Stellantis notes that the diagnosis must follow the code the transmission stores. So P0700 does not describe any specific fault: the useful code is in the transmission module.
Warnings and stop conditions
- Mediumeditorial warning
If the gearbox stays in one gear, acceleration and speed are reduced; avoid motorways and overtaking until it is checked.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100
Symptoms and causes
Probable causes · in order
- Fault stored in the transmissionCommon
The transmission module stored its own code (sensor, solenoid, park position, etc.). It is only known by reading that module.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100 · Stellantis STAR case S2321000006 DTC P0700 Transmission Control System (MIL Request)
- Communication between modulesPossible
GM documents P0700 alongside lost communication codes caused by backed-out terminals, chafed wiring or corroded connectors. Suspect it if U codes appear.
Evidence: GM TSB 08-07-30-021G GMLAN communication DTC U0100
- Module softwareLess common
In a Stellantis case, the transmission module software reported the code incorrectly to the scan tool.
Evidence: Stellantis STAR case S2321000006 DTC P0700 Transmission Control System (MIL Request)
Virtual technician
Does P0700 still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
GM TSB 08-07-30-021G GMLAN communication DTC U0100
General Motors LLC · 2012 · service_bulletin
- 2
California Air Resources Board · 2006 · official_doc
- 3
Stellantis STAR case S2321000006 DTC P0700 Transmission Control System (MIL Request)
Stellantis US LLC · 2023 · service_bulletin
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