P0870 Transmission Fluid Pressure Sensor/Switch C Circuit

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0870 DIAGNOSTIC Get a fair and transparent estimate upfront
Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0870 code

P0870 is a diagnostic trouble code (DTC) for "Transmission Fluid Pressure Sensor/Switch C Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0870 DIAGNOSTIC Get a fair and transparent estimate upfront

P0870 code definition

A P0870 code indicates that the powertrain control module (PCM) has determined that the pressure of the transmission fluid is not within the desired range.

What the P0870 code means

The P0870 is an OBD-II generic code and it will occur if transmission fluid increases or decreases to a level that is not within the programmed limits.

What causes the P0870 code?

There are several reasons that the P0870 can occur:

  • Low transmission fluid
  • Faulty transmission high pressure pump
  • Defective transmission (also called a slipping transmission)
  • Defective temperature sensor
  • Engine overheating
  • Failing or defective PCM

What are the symptoms of the P0870 code?

The P0870 code triggers the code and also the service engine light. Most mechanics or technicians also say that a major sign that this code is going to appear is the smell of the transmission fluid as it overheats, and the smoke that may appear. Drivers will experience transmissions that slip out of gear or which are impossible to put into gear and use.

How does a mechanic diagnose the P0870 code?

Though the P0870 is diagnosed with an OBD-II scanner, one of the very first steps is to check the transmission before doing any other diagnostics as this may be the source of the code. The technician should also look at freeze frame determine when and where (in the order of events) the code was set. Once they check the transmission, they can reset the fault codes and test the vehicle to see if the code reappears.

The technician will use the scanner to diagnose any electrical issues with the system and examine the wiring, repairing and replacing components when needed. Unplugging the electrical connector and testing the sensor for voltage is also part of the process and if it is not in compliance, it may need to be replaced.

Common mistakes when diagnosing the P0870 code

The P0870 code can cause many mistakes because it may lead to a technician feeling that the only problem is a transmission leak. This is why the first step is always to do a thorough diagnostic on the transmission to be sure that high temperatures have not damaged it internally. Only when the transmission has been assessed fully and repaired should the diagnostics on the sensor be performed.

How serious is the P0870 code?

The P0870 code is very serious because it can easily lead to the destruction of the transmission. Mistaking it for low fluid levels, rather than a full-blown leak is a common blunder. This code should not be taken lightly because it may mean a much costlier repair down the road.

What repairs can fix the P0870 code?

To overcome and repair the P0870 code, a mechanic must:

  • Perform a full transmission inspection and diagnostic to be sure that any leaks are repaired and that the right amount of fluid is in the tank. If the fluid smells very burnt before the inspection and the code is set, it could be that a new transmission is needed.
  • Retesting after transmission repairs is necessary and if the code returns, a diagnosis of the electrical circuitry for the sensor is needed. Visually examining the wiring and replacing or repairing anything that is corroded, melted, shorted, or disconnected is necessary.
  • If the code persists, the transmission temperature sensor must be unplugged and tested for its reference voltage. If it is within the manufacturer's guidelines, test the ground and resistance. If it fails, replace it.
  • Checking the PCM is important as this could also be the issue, though it is rare.

Additional comments for consideration regarding the P0870 code

Don't rush to replace the sensor when it could be a transmission leak. Also, be aware that control modules can fail, such as the PCM, but it is not a common reason for this code to appear.

Need help with a P0870 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6220.

trouble codes
P0870
Check Engine Light

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0870 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

4,810

Rating Summary
4,424
187
47
28
124
4,424
187
47
28
124

Joel

19 years of experience
741 reviews
Joel
19 years of experience
Acura RL - Check Engine Light is on - Jacksonville, Florida
very knowledgeable and precise. able to fix electrical issues in my car. Right on time for the appointment.

Christopher

15 years of experience
41 reviews
Christopher
15 years of experience
Honda Accord - Check Engine Light is on - Fairburn, Georgia
Christopher was excellent! He explained everything in detail to make sure I understood. He was professional and provided me with the next course of actions to resolve my care issues. I'm glad he was sent to service my car.

Alexander

18 years of experience
58 reviews
Alexander
18 years of experience
Saab 9-7x - Check Engine Light is on - Kissimmee, Florida
He was very friendly and very helpful . I felt like it was being around a close friend , also gave me so very good advice on my car & future advice about it . Highly recommend mechanic, would use his services again .

Matthew

31 years of experience
639 reviews
Matthew
31 years of experience
Jeep Patriot - Check Engine Light is on - Norfolk, Virginia
Matthew was on time which was a relief, he is very knowledgeable and was easy to understand what was wrong and what was being done. I am recommending to friends and family due to the great experience Matthew gave me. Extremely professional 10/10

More related articles

Related questions

Car keeps dying after a few minutes of driving

A car that dies after it warms up is a sign of an electrical module that can no longer handle the heat it is generating. Which module it is will require someone to diagnose it. What I would need to...

Oil pressure drops to 0 "stabilitrak" issue across message center traction control shuts off but oil sending unit was just replaced

The first thing to do is to have the Check Engine Light scanned to see what code is stored. Once this is done, then the code should be diagnosed to see if it has anything to do with the previous...

AC failed and started running rough and the Check Engine Light came on. But NOW its fine.

I wouldn't concern yourself with the timing of your cars symptoms. When a car fails, I liken it to when a light bulb decides to burn out. It was just its time. Everything will eventually fail. I also would strongly...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1-800-701-6230 · hi@yourmechanic.com