Transmission Control System (MIL Request)
What it means
This code does not name a specific fault. It means the transmission control module (TCM) has stored a fault of its own and asked the engine computer to turn on the check engine light. The real fault is stored in the TCM and must be read with a scan tool that can access the transmission module.
Related lights
Dashboard lights that may come on with this code.
Symptoms4
- Check engine light on, sometimes with a transmission warning light or message.
- Transmission in limp mode, stuck in one or two gears.
- Harsh or delayed shifts.
- Weak acceleration, or engine speed rising without a matching gain in road speed.
Possible causes6
- A faulty transmission sensor, such as a speed sensor or the fluid temperature sensor.
- An electrical fault in a shift or pressure control solenoid or its wiring.
- Low, degraded or burnt transmission fluid.
- Internal clutch slipping that sets an incorrect gear ratio code.
- A faulty or misadjusted transmission range sensor.
- A fault or software problem in the TCM itself (less common).
How to diagnose5
- Read the codes stored in the TCM with a scan tool that supports it; they identify the actual fault.
- Check the transmission fluid level, color and smell using the manufacturer procedure.
- Inspect the connectors and wiring to the transmission for corrosion, fluid intrusion or damage.
- Watch live transmission data such as input and output speeds, fluid temperature and commanded gear during a road test.
- Follow the test steps for the specific code found in the TCM.
How to fix6
- Top up the transmission fluid to the correct level with the fluid type the manufacturer specifies.
- Repair any damaged wiring or connector found during testing.
- Replace the sensor or solenoid indicated by the TCM code.
- Update the TCM software if the manufacturer has released an update for the problem.
- Repair the transmission internally if slipping or mechanical damage is confirmed.
- Clear codes from both modules, then road test and confirm the code does not return.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
In the Saudi market: SAR 150–5,000 (≈ USD 40–1,330)
Our prices come from the Saudi market, converted at a fixed rate (SAR 3.75 per USD). Prices in your country may differ a lot, so we show the cost level.
The cost depends entirely on the code stored in the TCM: it is low for a fluid top-up or connector repair, and much higher when internal repairs or a valve body are needed.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Why doesn't P0700 show the real fault?
Because it is only a message from the TCM asking the engine computer to turn on the light. The detailed fault is stored in the TCM, and some basic scan tools cannot read that module.
Can I drive with this code?
Short distances and gently if the shifts feel normal. If the transmission is in limp mode or slipping, limit driving and have it checked soon to avoid further damage.
Will a transmission fluid change fix it?
It may if the fluid is low or degraded, but do not change it before reading the TCM code to find the actual cause.
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