P0842 means Transmission Fluid Pressure Sensor/Switch A Circuit Low. The circuit for transmission fluid pressure switch or sensor A is reading low. It is a generic OBD-II code, so the definition is the same on any make, but the most likely cause varies by engine; confirm with a scan tool and the service information for your vehicle before buying parts.
What P0842 means
Electronically controlled automatics are run by a transmission control module (TCM), a separate box or part of the engine computer. It reads speed sensors, the range sensor and fluid temperature to decide when to shift, and drives solenoids that apply clutches and the torque converter clutch. Many basic code readers only show the generic P0700; a scan tool that reads the transmission module shows the specific fault. Check fluid level and condition first, since low or burnt fluid causes many transmission codes.
P0842 symptoms
- Harsh or erratic shifts
- Limp mode
- Check engine light
Common causes of P0842
- Shorted pressure switch or sensor
- Internal harness damage
- Low fluid level
How to diagnose P0842
- Check transmission fluid level and condition first
- Check the switch circuit for shorts
- Inspect the internal harness
Can you drive with P0842?
With caution; repair soon.
P0842 tips
Pressure switch circuits run through the internal harness, so a pinched harness after pan work is a common cause. Check the fluid level as well.
Will P0842 clear itself?
If the fault stops, the computer turns off the check engine light by itself after several drive cycles without seeing it again, and the code stays in memory as history for a while. Clearing P0842 with a scan tool after a repair is fine, but if the cause is still there the code returns, sometimes within one drive. Disconnecting the battery also clears codes on most vehicles, but it erases learned fuel trims and idle settings as well.
Related codes
| Code | Meaning |
|---|---|
| P0841 | Transmission Fluid Pressure Sensor/Switch A Circuit Range/Performance |
| P0868 | Transmission Fluid Pressure Low |
| P0846 | Transmission Fluid Pressure Sensor/Switch B Circuit Range/Performance |
Guides that help
When it is more than a sensor
If the fault turns out to be internal (worn clutches, a failed converter or a damaged valve body), compare a rebuild with a replacement in transmission rebuild vs replacement and transmission replacement cost, identify your unit with what transmission do I have?, and browse our transmissions.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.