What Does It Mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to all vehicles from 1996 onwards (Ford, Honda, Mazda, Mercedes, VW, etc.). Although generic, specific repair steps may vary by make/model.
If your vehicle’s dashboard has displayed a malfunction indicator lamp (MIL) along with a stored code P0701, it simply means the powertrain control module (PCM) has detected a malfunction in the transmission control system. This code applies exclusively to vehicles equipped with automatic transmissions.
What Does It Mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to all vehicles from 1996 onwards (Ford, Honda, Mazda, Mercedes, VW, etc.). Although generic, specific repair steps may vary by make/model.
If your vehicle’s dashboard has displayed a malfunction indicator lamp (MIL) along with a stored code P0701, it simply means the powertrain control module (PCM) has detected a malfunction in the transmission control system. This code applies exclusively to vehicles equipped with automatic transmissions.
While most transmission controllers (for OBD-II equipped vehicles) are integrated into the PCM, some manufacturers still choose to use a standalone transmission control module (TCM). Transmission-related codes are stored as P-codes, regardless of the system type equipped on a particular vehicle (there are no T-codes). If code P0701 is stored, it’s very likely other transmission control codes are also stored.
Automatic transmissions in OBD-II equipped vehicles are electronically controlled. This involves a control module, a controller area network (CAN), numerous sensors and solenoids, a powerful hydraulic pump, and a hydraulic valve body.
The transmission controller receives voltage input signals from engine and transmission sensors. Engine sensor inputs include (but aren’t limited to) throttle angle, engine RPM, load percentage, and coolant temperature. Transmission sensor inputs help monitor pump pressure, transmission input speed (RPM), transmission output speed (RPM), gear lever position, vehicle speed, torque converter lockup percentage, and transmission temperature, to name a few. The transmission controller uses these input signals to map shift strategy and electronic pump pressure settings. The electronic pressure control valve is used to regulate pump pressure and maintain smooth transmission operation. If maximum pump pressure were applied directly to the valve body, shifting would instantly become extremely harsh and transmission components could be damaged. Electronically controlled solenoids actuate spring-loaded spool valves to restrict and release high-pressure fluid through hydraulic circuits, causing upshifts and downshifts as desired. Yet another solenoid controls the torque converter lockup percentage, increasing energy efficiency and road power.
The CAN is a complex wiring and connector system used to transmit data from the TCM (if applicable) and PCM. Data (including stored codes) can also be shared with other controllers via the CAN. Transmission input and output speed (RPM), vehicle speed, and transmission temperature are all shared among various controllers. This data is used for comparison purposes in anti-lock braking systems, electronic traction control systems, and electronic stability control systems (among others).
This code is unique in that it’s typically only stored if other transmission-related codes are present. These could be codes related to mechanical or electrical issues.
Symptoms
and Severity
If this code is stored, you may have noticed your transmission shifting much harder than normal. This is because the transmission control system is placed in limp mode. In this mode, transmission pump pressure is significantly increased. This mode isn’t intended for long-term use. If your vehicle has displayed a P0701 code, it should be diagnosed immediately.
Symptoms of a P0701 code may include:
Irregular transmission shifting patterns
Transmission failure to shift
Reduced energy efficiency
Transmission slipping
Delayed transmission engagement
Other transmission-related codes
Causes
Causes
Possible causes for setting this code are as follows:
Low transmission fluid level
Inferior quality transmission fluid
Transmission sensor failure
Open or shorted circuits in the transmission control system
Mechanical transmission failure (internal)
Torque converter defects
Faulty transmission controller or PCM programming error
Diagnostic and Repair Procedures
A good starting point is always to check technical service bulletins (TSBs) for your specific vehicle. Your problem may be a known issue with a known fix published by the manufacturer and can save you time and money during diagnosis.
A scanner, digital volt/ohmmeter, transmission pressure gauge, and vehicle service manual (or equivalent) may be needed to diagnose a P0701.
Start with a visual inspection of transmission control wiring and connectors. Also test the battery, check battery cables and battery terminal ends at this stage.
Connect the scanner to the vehicle’s diagnostic connector and retrieve all stored codes and freeze frame data. Note this information and keep it for later.
Since the primary cause of transmission failure is due to fluid level and/or condition, the fluid should be checked now. Follow manufacturer specifications for
checking transmission fluid level.
If the fluid has a sharp burnt smell, suspect catastrophic mechanical failure that will require complete transmission rebuild and new torque converter. If fluid level is low by more than one quart, fill transmission with recommended transmission fluid and start engine. Inspect transmission, transmission cooler, and cooler lines/pipes for leaks. Repair leaks as needed. Once leaks are repaired and fluid level corrected, test drive vehicle to see if code/s reset. If they don’t, then the code was related to low fluid condition and has been corrected.
If code/s reset immediately, return to your recorded freeze frame data. Start by diagnosing the code that was stored first and diagnose/repair all other stored transmission control codes before attempting to diagnose P0701.
Additional Diagnostic Notes:
Diagnose and repair all other transmission-related codes before attempting to diagnose this code
Low transmission fluid level is a common cause of transmission failure
Transmission maintenance at recommended intervals can extend longevity