P0737: Transmission Control Module Engine Speed Output Circuit
What to do
Often no effect on how the car drives. Check whether the rev counter still works — if it does, this fault is affecting something else and is worth identifying but not urgent.
What this code means
A fault in the engine speed signal the transmission module sends out rather than the one it receives. On vehicles where the transmission module relays engine speed onward — to the instrument cluster, or to another module that needs it — this circuit is that output, and a fault here does not affect how the transmission itself shifts.
That makes it one of the less alarming codes in the block. The consequence is usually confined to whatever was reading the signal: a rev counter that has stopped working, or another system quietly losing an input it used. Worth confirming which, since the answer determines whether it matters at all.
Likely causes
Start here
- Open circuit in engine speed wiring · moderate
- Corroded or loose connector · easy
Less common
- Faulty transmission control module · specialist
- Poor module ground connection · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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