A transmission fault detected by the TCM; the specific code stored there identifies it (OBD-Codes.com). Defective shift solenoids (RepairPal). Defective engine coolant temperature sensor (RepairPal). Defective valve body (RepairPal). Dirty transmission fluid restricting the hydraulic passages (RepairPal). Rarely, a failed TCM or PCM (OBD-Codes.com calls this unlikely).

Diagnose and repair the specific transmission code stored in the TCM. Replace faulty shift solenoids or the valve body. Service dirty transmission fluid. Replace a faulty engine coolant temperature sensor. Repair or replace the TCM only if diagnosis confirms it has failed.

P0700🔧 Transmission / transmission control moduleStop and fix promptly

P0700: Transmission Control System Malfunction (Meaning, Causes, Fixes)

Q: What does P0700 mean?

P0700 means the transmission computer (TCM) has found a fault and told the engine computer to turn on the check engine light. P0700 itself doesn't say what's wrong: you need a scan tool that can read the transmission module to find the specific transmission code behind it. Many vehicles have a separate transmission control module (TCM) for the automatic transmission. OBD-Codes.com explains that when the TCM detects a fault and stores a transmission code, it informs the engine computer (ECM/PCM), which sets P0700 and turns on the check engine light. That makes P0700 a pointer: at least one more code is stored in the TCM. RepairPal agrees that the TCM sends a message to the PCM to set P0700 and that additional codes are usually stored in the TCM. RepairPal's detail section adds a more specific description, saying P0700 means the PCM is seeing more than a specified RPM difference between the transmission's input and output speed sensors, which often implies the transmission is slipping. OBD-Codes.com doesn't describe it that way, so treat that as one possible trigger rather than the definition.

Q: Can I keep driving with P0700?

Stop and fix promptly. Get it checked soon, and drive gently until you do. RepairPal rates P0700 'Urgent' and lists improper shifting among its symptoms; OBD-Codes.com says the transmission may show drivability problems like slipping. If the transmission is slipping, shifting harshly, stuck in one gear, or the car stalls when coming to a stop, avoid highway driving and have it diagnosed before more damage is done. Sources frame it differently: OBD-Codes.com calls P0700 an informational code that only tells you a transmission code is stored in the transmission computer, while RepairPal treats it as an urgent fault. Either way, the real problem is in the transmission code(s) you haven't read yet.

Reviewed 2026-10-22 · Based on 2 cited source(s)

What P0700 means

Many vehicles have a separate transmission control module (TCM) for the automatic transmission. OBD-Codes.com explains that when the TCM detects a fault and stores a transmission code, it informs the engine computer (ECM/PCM), which sets P0700 and turns on the check engine light. That makes P0700 a pointer: at least one more code is stored in the TCM. RepairPal agrees that the TCM sends a message to the PCM to set P0700 and that additional codes are usually stored in the TCM. RepairPal's detail section adds a more specific description, saying P0700 means the PCM is seeing more than a specified RPM difference between the transmission's input and output speed sensors, which often implies the transmission is slipping. OBD-Codes.com doesn't describe it that way, so treat that as one possible trigger rather than the definition.

Severity: can I keep driving?

Stop and fix promptly

Get it checked soon, and drive gently until you do. RepairPal rates P0700 'Urgent' and lists improper shifting among its symptoms; OBD-Codes.com says the transmission may show drivability problems like slipping. If the transmission is slipping, shifting harshly, stuck in one gear, or the car stalls when coming to a stop, avoid highway driving and have it diagnosed before more damage is done. Sources frame it differently: OBD-Codes.com calls P0700 an informational code that only tells you a transmission code is stored in the transmission computer, while RepairPal treats it as an urgent fault. Either way, the real problem is in the transmission code(s) you haven't read yet.

Common symptoms

Check engine light on (both sources)
Transmission won't shift properly (RepairPal)
Drivability problems such as slipping (OBD-Codes.com)
Decrease in fuel economy (RepairPal)
Stalling when coming to a stop after highway driving, or misfire-like symptoms, in some cases (RepairPal)
In unusual cases, no noticeable symptoms (RepairPal)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

A transmission fault detected by the TCM; the specific code stored there identifies it (OBD-Codes.com)
Defective shift solenoids (RepairPal)
Defective engine coolant temperature sensor (RepairPal)
Defective valve body (RepairPal)
Dirty transmission fluid restricting the hydraulic passages (RepairPal)
Rarely, a failed TCM or PCM (OBD-Codes.com calls this unlikely)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read the transmission codes. OBD-Codes.com says the only real solution is a scan tool that can communicate with the transmission control module; many basic code readers only show engine codes, so check that yours supports transmission/TCM codes, or have a parts store or shop scan it.
If a TCM-capable scan tool can't communicate with the transmission module at all, OBD-Codes.com says that's a good indication the TCM itself may be faulty.
Check the transmission fluid level and condition if your vehicle has a dipstick and the owner's manual describes the procedure; RepairPal lists dirty fluid as a common cause.
Note when the problem happens (speed, throttle, warm or cold). RepairPal says technicians should record freeze frame data and reproduce the conditions on a test drive, because P0700 can be hard to catch.

Typical fixes

Diagnose and repair the specific transmission code stored in the TCM
Replace faulty shift solenoids or the valve body
Service dirty transmission fluid
Replace a faulty engine coolant temperature sensor
Repair or replace the TCM only if diagnosis confirms it has failed

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

Your scanner can't read transmission codes
The transmission is slipping, shifting harshly, or stuck in one gear
Diagnosis needs live input/output speed and lockup solenoid data, which RepairPal describes as a shop-level test
Valve body, solenoid, or internal transmission work is needed

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Does P0700 mean my transmission is bad?

Not necessarily. It means the transmission computer has stored a fault code. Causes listed by RepairPal range from shift solenoids and dirty fluid to a coolant temperature sensor. RepairPal lists 'internal transmission problem' among common misdiagnoses, so read the TCM code before assuming the worst.

Why does my code reader only show P0700?

Many basic readers only see the engine computer. P0700 is the engine computer's flag that the transmission computer has its own code, and OBD-Codes.com says you need a scan tool that communicates with the transmission module to read it.

Can a misfire be confused with P0700?

RepairPal lists an engine misfire problem and driveline problems as common misdiagnoses for P0700, and notes some cars show misfire-like symptoms. Check for misfire codes such as P0300 too.

Sources

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.