C0901 code meaning
TPMS Sensor 1 Position Performance
What C0901 means
Nothing public ties C0901 to a carmaker: no public code list, NHTSA bulletin or service index contains it. Its title concerns the automatic assignment of wheel transmitter 1 to a corner of the car. Without that link the system knows a pressure value but not which tire it belongs to. Saab's 9-5 of 2011 learns the side from the sensor's turning direction and the axle from signal strength, which takes 3 to 9 minutes of driving. A Schrader patent instead compares the phase angle each sensor reports with ABS tooth counts and picks the best matching wheel. Land Rover's TPM module sets C1D18-55 while locations are still unknown and clears it after 10 minutes above 20 km/h. A performance fault means the learning did not finish or gave a doubtful result.
C0901 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyEasy, DIY possible
- Typical labor0.2 to 1 hours
- Clears after repairAfter a drive cycle
Symptoms of C0901
- TPMS warning lamp lit or flashing although tire pressures are correct
- Pressures shown at the wrong wheel position or no position display at all
Common causes of C0901
- Most likelyLearning drive too short or too slow after wheel change or sensor replacement
- PossibleWheel speed data from the ABS module missing or implausible, so phase comparison fails
- Less likelyTransmitters of a spare wheel or a nearby vehicle disturbing the assignment
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Tpms sensorTpms receiver
What each part of C0901 means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 01 | The exact fault in that area. |
What to do next
- Note C0901 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 C0901
What does C0901 mean?
C0901 means "TPMS Sensor 1 Position Performance". Nothing public ties C0901 to a carmaker: no public code list, NHTSA bulletin or service index contains it. It is a generic code, so it means the same on every make.
Is it safe to drive with C0901?
C0901 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will C0901 fail an emissions test?
C0901 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C0901 to fix?
Difficulty: easy. A typical repair takes 0.2 to 1 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will C0901 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.