Fault code P0700 – a step-by-step guide to diagnosing and fixing it

DTC P0700 indicates that there is an issue with the automatic transmission system. Automatic vehicles have a transmission control module (TCM) (TCM) which monitors the system for malfunctions. If it detects a problem, the module will transmit this information to the engine control module, triggering the trouble code.

• A defective shift solenoid. This will disrupt the flow of hydraulic fluid in the car, obstructing the transfer of power to the transmission gears. This usually occurs due a build-up of dirt or deposits, blocking the valve’s moving parts. There may also be a problem with the circuit or connection.
• TCM failure. The component may fail as a result of a bad circuit board or corrosion due to exposure to harsh conditions.
• A clogged or dirty valve body. This will stop the ATF from circulating properly.
• An ATF leak. The fluid can leak out if the seals crack and harden due to exposure to extreme heat or debris. This can also occur due to a worn transmission pan or pan gasket. A lack of ATF can cause the gears to slip.
• Broken wires or a short circuit. This could be due to thermal or mechanical damage as the insulation can melt under high temperatures and electrical components may be affected by vibrations or corrosion. This will affect the exchange of data between the sensors, actuators and ECU.

• Activation of the emergency transmission mode (for serious failures)
• A poor fuel economy
• Driveability problems, such as stalling, a rough engine, or slipping gears
• Delayed gear engagement
• A noisy transmission
• A puddle of oily fluid or stains underneath the vehicle (usually red or brown fluid)

• Scan the onboard computer with an OBD2 scanner to check the registered DTCs and freeze frame data. This will help you to quickly determine the root of the problem and possible solutions. P0700 is normally accompanied by other codes, e.g. P0750 - P0780. Reset the DTCs to rule out false errors, caused by a low voltage or a failing alternator in the car, etc.
• Clean out the valve body to remove build-ups and impurities and restore the flow capacity. This is usually done professionally at a car workshop using special equipment. However, it may be possible to clean it with a transmission cleaning agent or brake cleaner.
• Clean the electrical contacts with a hydrophobic cleaning agent to get rid of any dirt, debris and rust, as well as prevent corrosion.
• Check the ATF level and the condition of the fluid. It should be a clear reddish colour and free of contaminants. If the fluid is too dark or gritty, it should be changed. Experts recommend changing the fluid every 25,000;40,000 km. Top up the fluid as required. The cause of low ATF levels is often a leak. Make sure to inspect the seals and pan gasket. Replace if necessary.
• Test whether the shift solenoids are functioning properly by measuring the electrical resistance with a multimeter. Broken wires and electrical connectors should be replaced to restore the electrical connectivity within the system.