# P0700: Transmission Control System (MIL Request) **Verdict:** Drive to a shop this week Transmission - Generic OBD-II code, applies to all gasoline cars and light trucks sold in the US since 1996. - **Typical cost:** $100-$5,500 - **Urgency:** This week - **Most likely:** Another transmission fault (see TCM codes) - **DIY?:** Read TCM codes first ## Quick answer P0700 means the transmission computer has found a problem and asked the engine computer to turn on the check engine light. It does not say what the problem is by itself, so the real answer is in the transmission computer's own codes, which a basic code reader may not show. You need a scan tool that can read transmission codes. ## What does P0700 mean? Most automatic transmissions have their own transmission control module (TCM), or share a combined powertrain module, that runs the shift solenoids and watches the speed sensors, fluid temperature, and pressure switches. On most vehicles the TCM does not control the check engine light directly. When it finds a fault, it stores its own detailed code and sends a request to the engine computer to turn the light on. P0700 is that request, stored in the engine computer. It means only that the transmission computer has a problem on file, not what the problem is. The detailed code, such as P0715 for an input speed sensor or P0730 for an incorrect gear ratio, sits in the TCM's memory. Basic code readers often show only P0700, so you need a scan tool that can read transmission data to see the actual cause. ## What are the symptoms of P0700? - Check engine light on - Harsh, delayed, or slipping shifts - Transmission stuck in one gear (limp mode) - Transmission warning light on some cars ## What causes P0700? Ranked from most to least likely. Check them in this order: the cheap, common causes first. 1. **A specific transmission fault stored in the transmission computer** (most common). P0700 is a flag, and the real fault is stored in the transmission computer as another code, such as P0715 for an input speed sensor or P0730 for an incorrect gear ratio. Those codes point to the system involved. Reading them with a capable scan tool is the first step and decides whether the repair is small or major. 2. **Low or burnt transmission fluid** (common). Transmission fluid cools, lubricates, and supplies the hydraulic pressure that applies the clutches. Low fluid from a leak, or fluid that is dark and burnt from heat and age, can cause pressure and slip faults that the transmission computer detects. Vehicles used for towing, hauling, or hot stop-and-go driving wear out fluid faster. 3. **Failed shift solenoid or speed sensor** (common). Shift solenoids, pressure control solenoids, and speed sensors are electrical parts inside or on the transmission. Heat, vibration, and debris in the fluid can make them stick or fail, triggering codes that come with P0700. Some are external and inexpensive to replace, while others sit inside the pan or on the valve body. 4. **Wiring or connector problem at the transmission** (less common). The transmission harness carries many signals through connectors that sit near hot exhaust parts and can collect fluid or road grime. Corroded pins, a leaking connector seal where the harness passes into the case, or a damaged wire can cause intermittent shifting problems and several codes at once. Faults that change with temperature or bumps often point here. 5. **Transmission computer fault** (rare). The transmission control module itself can fail internally from water entry, heat, or a voltage spike, and on some vehicles the maker releases software updates for shift problems. Because a module is expensive and may need programming, a shop first confirms its power, ground, and wiring, and replaces it only when every other check passes. ## How do you diagnose P0700? 1. Use a scan tool that can read transmission control module (TCM) codes, and write down every code stored. 2. Check transmission fluid level and condition, following your vehicle's procedure. 3. Diagnose the specific transmission code or codes found. 4. Inspect wiring and connectors at the transmission and the TCM. ## How do you fix P0700, and what does it cost? | Fix | Typical cost | What it involves | | --- | --- | --- | | Transmission fluid service | $150-$350 | Helps only if fluid is low or old and no internal damage is present. | | Replace shift solenoid or speed sensor | $250-$800 | Depends on whether the part is external or inside the transmission pan. | | Rebuild or replace transmission | $2,800-$5,500 | Only when internal damage is confirmed. | ## Is it safe to drive with P0700? > **Drive to a shop this week.** Drive gently and only as needed. If the transmission is slipping, stuck in one gear, or shifting harshly, avoid highways and get it diagnosed soon to prevent further damage. ## Will P0700 fail an emissions test? A check engine light with P0700 stored fails an OBD-II emissions test in most states, even though the fault is in the transmission. Clearing the codes resets the engine's readiness monitors too, so the car may be rejected as not ready. Fix the underlying transmission code before testing, because P0700 returns whenever that fault does. ## After the repair: clearing P0700 After the repair, clear codes in both the transmission and engine computers, since clearing only one may leave the light on. Many modern transmissions need their adaptive shift values reset or relearned after solenoid, valve body, or fluid work, using a scan tool or a set drive pattern. Smooth shifts and no returning codes mean success. ## How to prevent P0700 - Have the transmission fluid checked at the intervals in your owner's manual. - Follow the severe-service fluid schedule if you tow, haul heavy loads, or drive in stop-and-go heat. - Use only the exact transmission fluid type listed for your vehicle, since the wrong fluid can cause shift faults. - Fix transmission fluid leaks early, because running low quickly overheats clutches and solenoids. - Get flaring, slipping, or harsh shifts checked promptly rather than waiting for limp mode. ## Codes often seen with P0700 - [P0715](/codes/p0715): Input/Turbine Speed Sensor "A" Circuit - [P0730](/codes/p0730): Incorrect Gear Ratio - [P0741](/codes/p0741): Torque Converter Clutch Solenoid Circuit Performance/Stuck Off - [P0500](/codes/p0500): Vehicle Speed Sensor "A" ## Frequently asked questions ### Can I drive with a P0700 code? You can usually drive carefully to a shop, but it depends on the underlying transmission fault. If the transmission slips, shifts harshly, or is stuck in one gear, keep trips short and slow and avoid highways. Continuing to drive a slipping transmission can turn a small repair into a rebuild. ### Why does my code reader only show P0700? Basic code readers often read only engine codes, and P0700 is the engine computer's note that the transmission computer has a fault. A scan tool that reads transmission codes will show the specific problem. Many shops have one, and a proper scan usually costs less than guessing at parts. ### Does P0700 mean my transmission is bad? Not necessarily, since many P0700 causes are sensors, solenoids, wiring, or low fluid. The specific transmission code tells you whether it is a small repair or a major one. Even when symptoms feel serious, such as limp mode, the cause can be a single faulty sensor or connector. ### How much does it cost to fix P0700? It depends entirely on the underlying fault. A fluid service runs about $150 to $350, an external sensor or solenoid about $250 to $800, and a rebuild or replacement $2,800 to $5,500 when internal damage is confirmed. Pay for a full transmission scan before agreeing to any major repair. ### What is transmission limp mode? Limp mode is a protective setting in which the transmission computer holds one gear, often second or third, so you can drive slowly to a shop without causing more damage. It often comes on with P0700 when a serious fault is found. The car feels sluggish from a stop and revs high at speed. ### Can I clear P0700 myself? You can clear it with a scan tool, but it will return if the underlying transmission fault is still present. Clearing also erases the freeze-frame data and detailed codes a technician needs to diagnose it. Read and write down every code from both computers before you clear anything. ### Can low transmission fluid cause P0700? Yes, low or burnt fluid can cause pressure or slipping faults that make the transmission computer request the check engine light. Many newer transmissions have no dipstick and must be checked at a set fluid temperature, often by a shop. Add only the fluid type your vehicle specifies. ### Can a bad battery cause P0700? It can on some vehicles. Low system voltage can make solenoids and the transmission computer misbehave and store faults, sometimes alongside P0562. If P0700 shows up with a weak battery, dim lights, or a charging warning, fix the voltage problem first, then clear the codes and see whether they return. ### Will P0700 fail an emissions test? Yes, in most states a lit check engine light fails an OBD-II emissions test, and P0700 exists to turn that light on. Repair the transmission fault first. After clearing codes, drive normally for several days so the engine's readiness monitors can complete before you return for the test. ### Can I fix P0700 myself? You can do the first steps: read every code with a transmission-capable scan tool and check the fluid if your car has a dipstick. Replacing an external speed sensor is often manageable too. Internal solenoids, valve bodies, and relearn procedures usually need a shop with the right tools and data. ## Sources - [SAE J2012: Diagnostic Trouble Code Definitions](https://www.sae.org/standards/content/j2012_201812/) ## Other transmission codes - [P0705 Transmission Range Sensor "A" Circuit (PRNDL Input)](https://diagxcar.com/codes/p0705) - [P0715 Input/Turbine Speed Sensor "A" Circuit](https://diagxcar.com/codes/p0715) - [P0717 Input/Turbine Speed Sensor "A" Circuit No Signal](https://diagxcar.com/codes/p0717) - [P0720 Output Shaft Speed Sensor "A" Circuit](https://diagxcar.com/codes/p0720) - [P0730 Incorrect Gear Ratio](https://diagxcar.com/codes/p0730) - [P0731 Gear 1 Incorrect Ratio](https://diagxcar.com/codes/p0731) - [P0732 Gear 2 Incorrect Ratio](https://diagxcar.com/codes/p0732) - [P0740 Torque Converter Clutch Solenoid Circuit/Open](https://diagxcar.com/codes/p0740) - [P0741 Torque Converter Clutch Solenoid Circuit Performance/Stuck Off](https://diagxcar.com/codes/p0741) - [P0750 Shift Solenoid "A"](https://diagxcar.com/codes/p0750) - [P0122 Throttle/Pedal Position Sensor/Switch "A" Circuit Low](https://diagxcar.com/codes/p0122) - [P0123 Throttle/Pedal Position Sensor/Switch "A" Circuit High](https://diagxcar.com/codes/p0123) - [P0500 Vehicle Speed Sensor "A"](https://diagxcar.com/codes/p0500) - [P0562 System Voltage Low](https://diagxcar.com/codes/p0562) ## Symptoms - [Why does my car hesitate when I accelerate?](https://diagxcar.com/symptoms/car-hesitates-when-accelerating) - [Why does my car jerk when I accelerate?](https://diagxcar.com/symptoms/car-jerks-when-accelerating) - [Why is my car leaking transmission fluid?](https://diagxcar.com/symptoms/car-leaking-transmission-fluid) - [Why won't my car go into gear?](https://diagxcar.com/symptoms/car-wont-go-into-gear) - [Why is my transmission slipping?](https://diagxcar.com/symptoms/transmission-slipping) - [Why does my car whine when I accelerate?](https://diagxcar.com/symptoms/whining-noise-when-accelerating) ## Repair costs - [Transmission replacement cost](https://diagxcar.com/cost/transmission-replacement) ## Terms explained - [What is CVT?](https://diagxcar.com/glossary/cvt) - [What is Limp mode?](https://diagxcar.com/glossary/limp-mode) --- Source page: https://diagxcar.com/codes/p0700 Updated: 2026-11-03 General information, not a substitute for a qualified mechanic.