P0700 on a Jeep JK
P0700 means the transmission control system has detected a fault and requested that the PCM turn on the malfunction indicator lamp.
What triggers P0700 on a Jeep JK
2007–2011: 3.8L, 42RLE
P0700 is not the transmission diagnosis. The 42RLE control system has detected another transmission-related fault, and P0700 is the message that carries it across to the engine-side diagnostic system.
The code you actually need is the transmission-specific one stored with it.
2012–2018: 3.6L, W5A580
The same principle applies. P0700 tells you the transmission-control side has reported a problem. It does not tell you whether the underlying issue is hydraulic, electrical, sensor-related, communication-related or internal to the transmission.
Most common causes
There is no useful “replace this part first” ranking for P0700 itself. Treat it as a routing code:
- Another transmission-specific code is stored in the transmission controller
- Transmission sensor or solenoid circuit fault
- Wiring, connector, power or ground problem affecting transmission control
- Communication problem between modules
- Internal transmission or hydraulic fault
- TCM or PCM fault, after the supporting circuits are ruled out
P0700 is one of the worst codes to diagnose from a generic scanner alone. A basic reader will show you P0700 and stop there. The real information sits in the transmission module, which needs a tool that can read manufacturer-specific codes.
Related codes
- U0100 on a Jeep JK — lost communication with the PCM
- P0339 on a Jeep JK — intermittent crankshaft-position signal
- P0300 on a Jeep JK — engine-side misfire, useful for separating an engine complaint from a transmission complaint