P0804 — Shift/Timing Solenoid Intermittent
Drivable short-term, but fix now to avoid damage.
What P0804 means
This code means the transmission control module detected an intermittent (on-and-off) electrical problem in the shift/timing solenoid circuit, which controls when and how the transmission changes gears. It's often caused by a failing solenoid, corroded or loose connectors, chafed wiring, or low and dirty transmission fluid. Repairs usually start with inspecting the wiring and connectors, checking fluid, and replacing the solenoid or its harness if needed.
Common symptoms
- Check engine light is on
- Harsh, delayed, or erratic gear shifts
- Transmission slips or briefly loses power
- Vehicle drops into limp mode (limited gears)
- Shifting feels different or inconsistent from one drive to the next
Common causes
- Failing or worn shift/timing solenoid
- Corroded, loose, or damaged electrical connector
- Chafed or broken wiring in the solenoid circuit
- Low, dirty, or contaminated transmission fluid
- Faulty transmission control module (less common)
Typical repair cost
$150 – $700
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0804 code?
For short trips you usually can, but you shouldn't rely on it. The intermittent signal means the transmission could shift harshly or drop into limp mode without warning, so get it diagnosed soon and avoid long drives until it's fixed.
How much does it cost to fix a P0804 code?
It depends on the cause. A wiring or connector repair can run around 150 to 300 dollars, while replacing a shift solenoid typically lands between 250 and 700 dollars including labor. A faulty control module would cost more.
Is a P0804 code serious?
It can be. While the immediate fault is electrical and often inexpensive, ignoring it can lead to slipping, overheating, and real transmission damage that costs far more to repair, so it's worth addressing promptly.
Why does the P0804 problem come and go?
Because it's an intermittent fault, the issue may only appear with heat, vibration, or certain gear changes. Loose connectors, partially broken wires, or a solenoid that fails only under load are common reasons the code sets and clears on its own.