Definition of Code P0871
Code P0871 identifies a problem with the fluid pressure inside the transmission.
Code P0871 is often associated with codes P0867, P0868, P0869, P0870, P0872, P0873, P0874, P0875, P0876, P0877, P0878, and P0879.
What Does Code P0871 Mean?
P0871 is the generic OBD-II code for a fault involving the fluid pressure inside the transmission. This could mean there is too much pressure inside the transmission or not enough pressure inside the transmission. Often, a lack of transmission fluid pressure is caused by a shortage of transmission fluid. If fluid has leaked or escaped in another way due to a mechanical failure, there will not be adequate fluid levels inside the transmission for proper operation.
What Causes Code P0871?
Code P0871 has a number of common causes:
- Low transmission fluid
- Faulty transmission high-pressure pump
- Broken or dirty transmission temperature sensor
- Slipping or faulty transmission
- Faulty powertrain control module
- Overheating engine
What Are the Symptoms of Code P0871?
Code P0871 will inevitably cause the Check Engine light to illuminate on the vehicle’s dashboard. Around the same time, the smell of an overheating transmission may become noticeable. The smell is similar to that of burning oil. There may also be smoke in the transmission area, although this only occurs if there is an active fluid leak in the area.
Incorrect fluid levels can also cause shifting issues and transmission slipping. Automatic transmissions may struggle to shift at the right time.
How Does a Mechanic Diagnose Code P0871?
A mechanic will diagnose code P0871 with an advanced OBD-II code scanner that can retrieve the vehicle’s factory readings. The certified technician will display real-time fault codes and see exactly when code P0871 was stored. Then, the code will be reset, and the vehicle will be taken for a road test.
If the code reappears during the test, transmission fluid pressure is likely the culprit. The wiring will be tested using a multimeter and factory test points for the circuits surrounding the transmission. The technician will also check for loose, damaged, or corroded cables around the transmission sensor circuits. They will also inspect the transmission for visible fluid leaks.
Common Mistakes When Diagnosing Code P0871
There are a number of errors that commonly occur when code P0871 appears. Sometimes, the technician underreacts and simply refills or replaces the fluid in cases where the transmission needs to be rebuilt to function properly. Other times, the transmission itself is completely fine, and the fluid is simply low or too old to be useful. An overheating transmission is a serious issue, and for this reason, servicing an overheating transmission often involves completely removing the transmission. This is not always necessary.
How Serious Is Code P0871?
Code P0871 can be quite serious. It may indicate that the transmission is about to overheat or otherwise fail. The only way to avoid major repairs after code P0871 is to have the vehicle repaired immediately. If done, it is possible that the issue can be resolved relatively inexpensively and quickly. In any case, the problem should be diagnosed as soon as code P0871 appears.
What Repairs Can Fix Code P0871?
The most common repairs to resolve code P0871 are as follows:
- Repair or replacement of the transmission high-pressure pump
- Replacement of the transmission temperature sensor
- Replacing or repairing damaged or corroded wiring
- Repair or replacement of the powertrain control module
- Replacement of transmission fluid
- Rebuilding the transmission