P0787 trouble code definition
A P0787 trouble code is related to a vehicle’s automatic transmission and its shift solenoids that control the transfer of hydraulic fluid to change gears.
What the P0787 code means
P0787 is an OBD-II generic powertrain code for voltage problem with the shift/timing solenoid in that the reading being sent to the engine control unit (ECU) is too low according to the manufacturer’s parameters. When this happens, the ECU can think the transmission is in a different gear than what the transmission actual is in.
What causes the P0787 code?
A P0787 code can have a variety of causes, but the most common are:
- Faulty shift solenoids
- Damaged hydraulic fluid lines
- Low or dirty transmission fluid
- Internal transmission damage
- Faulty transmission control module
What are the symptoms of the P0787 code?
A P0787 can affect vehicles differently, but some drivers notice zero difference in performance at all. For others, the transmission will not shift out of gear or will experience harsh shifting or gear slipping. Some transmissions will also limit performance period, entering a transmission control module parameter known as “limp-mode.”
How does a mechanic diagnose the P0787 code?
Because shift solenoids actuate fluid transfer that actuates gear shifting, a P0787 can frequently be caused by low or dirty transmission fluid. Your mechanic will first check fluid levels to determine if the code is a result of low fluid. After that, a visual inspection of the external components and connectors will be next before diving into the shift solenoids. A professional OBD-II scanner can trigger shift solenoids to activate, with your mechanic paying close attention to each one. If one fails to activate, it will need to be replaced and new, clean fluid will need to be added.
Common mistakes when diagnosing the P0787 code
There can be instances where the circuit for the shift solenoids is bad instead of the solenoids themselves. This means wiring will need to be repaired and the transmission may need to be removed from the vehicle to do this.
How serious is the P0787 code?
The seriousness of a P0787 depends on how it affects the vehicle. If there is no noticeable side effects, it could just be intermittent and the code needs to be cleared and fluid needs to be added. If it’s causing shifting issues, the problem is more serious and will need immediate attention.
What repairs can fix the P0787 code?
The most common repairs for a P0787 are as follows:
Additional comments for consideration regarding the P0787 code
It’s important to pay close attention to how the vehicle shifts with a P0787 as it will typically indicate what will need to be replaced. Low fluid will typically cause noticeable differences.
Need help with a P0787 code?
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