P0728 code meaning
Engine Speed Input Circuit Intermittent
Powertrain system Generic code P07xx codes Check engine light
What P0728 means
The transmission module needs engine speed for converter slip, shift quality and to check the turbine speed. Today it almost always arrives over CAN from the engine module with a validity flag; only GM's 2007 Allison 1000 tables show a separate engine speed sensor read by the transmission module. P0728 means the engine speed signal at the transmission module drops out briefly. No manufacturer document available to us uses this code: GM's Allison 1000 detects jumps and noise of this input under P0726/P0727, and Saab's bus-based systems use those codes, too. By analogy with P0718/P0723 dropouts are counted. A loose contact in the signal or CAN circuit or an intermittent crankshaft sensor fault in the engine module is the likely cause; shifts may be harsh at times.
P0728 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0728
- Occasional transmission warning lamp
- Harsh shift now and then
- Converter clutch releases occasionally
Common causes of P0728
- Most likelyLoose contact in signal or CAN circuit
- PossibleSensor (if fitted) dirty or loose
- PossibleIntermittent crankshaft sensor fault in the engine module
- Less likelyTransmission module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine speed signalCAN busTransmission control module
What each part of P0728 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 7 | Area: transmission. |
| 28 | The exact fault in that area. |
What to do next
- Note P0728 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0728
What does P0728 mean?
P0728 means "Engine Speed Input Circuit Intermittent". The transmission module needs engine speed for converter slip, shift quality and to check the turbine speed. It is a generic code, so it means the same on every make.
Is it safe to drive with P0728?
Drive gently and only to a workshop. With P0728 the car can go into limp mode (reduced power) to protect itself.
Will P0728 fail an emissions test?
Yes, it can. P0728 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0728 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0728 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.