P0816 OBD-II Trouble Code: Downshift Switch Circuit

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0816 code

P0816 is a diagnostic trouble code (DTC) for "Downshift Switch 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 for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 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 $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0816 DIAGNOSTIC Get a fair and transparent estimate upfront

P0816 code definition

The P0816 code is a generic powertrain code related to the transmission, including sensor faults. In this case, the downshift switch circuit may have a malfunction.

Codes related to the P0816 include:

What the P0816 code means

When a P0816 code is stored, the Engine Control Module (ECM) has found a malfunction with the downshift switch circuit. The downshift switch circuit includes the switch, connectors and system wiring, and the mode actuator. Located near the shifter in the passenger compartment of the vehicle, the downshift switch is used on vehicles with an automatic transmission that can be shifted manually (an automated manual).

Using solenoids to actuate fluid transfer between hydraulic circuits for each gear, the ECM calculates the data and initiates downshifting or upshifting. When the vehicle’s ECM is sent a voltage reading or resistance signal that is outside of the manufacturer's preset parameters, a P0816 code can be stored.

What causes the P0816 code?

Several problems may cause a P0816 code including:

  • Damaged or defective transmission gear selection switch
  • Open or shorted gear selection switch harness
  • Liquids getting into the downshift switch
  • Damaged, corroded or poor electrical connection to the transmission gear selection switch

What are the symptoms of the P0816 code?

Symptoms of a P0816 code may include:

  • Check Engine Light may illuminate
  • There may be no symptoms other than a stored P0816 code
  • Manual shifter function may be disabled
  • Vehicle may go into “limp” mode
  • Overdrive light may flash

How does a mechanic diagnose the P0816 code?

A mechanic may use several methods to diagnose a P0816 trouble code, including:

  • Utilize an OBD-II scanner to check for a stored P0816 trouble code
  • Check for reference voltage and ground signals at the downshift switch
  • Check for reference voltage and ground signals at the downshift actuator
  • If either circuit is open, use a volt/ohmmeter to check for continuity
  • Test all connected circuits and switches for continuity and resistance
  • Visually inspect all wiring and connectors related to the downshift switch circuit for damage or corrosion

Common mistakes when diagnosing the P0816 code

A common cause of a P0816 code or malfunction in the downshift switch is simply liquids being spilled onto the switch. Often, this can be overlooked and the cause of the fault is assumed to be faulty transmission wiring.

How serious is the P0816 code?

Because a vehicle’s safe driving operation may be impacted due to faults that store a P0816 code, this code is considered a potentially serious code. When this code appears, it is recommended to immediately take your vehicle to your local service center or mechanic for repair and diagnosis.

What repairs can fix the P0816 code?

Several repairs can fix a P0816 trouble code and include:

Need Help with a P0816 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 1-800-701-6230.

Check Engine Light
trouble codes
P0816

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0816 code.

SCHEDULE P0816 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


More related articles

P0479 OBD-II Trouble Code: Exhaust Pressure Control Valve Intermittent
P0479 code means there is an out-of-the-ordinary voltage reading from the exhaust pressure control valve circuit often due to damaged wiring.
P0625 OBD-II Trouble Code: Generator Field/F Terminal Circuit Low
P0625 means there is an issue with the generator field control circuit often due too shorted connectors or a defective CAN bus.
P2653 OBD-II Trouble Code: B Rocker Arm Actuator Control Circuit Low Bank1
P2653 means an open or shorted circuit in the B rocker arm actuator control circuit in bank 1 due to broken oil control valve or low oil levels.

Related questions

Truck shutting off when running AC
Knowing what code is being stored and causing the Check Engine Light to come on will greatly help with diagnostics. I would ask for help from one of the mechanics at YourMechanic to come to you with a scan tool,...
I have a 2003 Subaru Forester and upon starting this morning it ran fine for a minute or two. Then the Check Engine Light came on.
Too much air flowing into the intake causes the engine to lean out too much air in relation to the fuel and misfire. At an idle, the PCV valve restricts air flow, to reduce this problem. At high manifold vacuum...
Check engine light on while driving after a drop in RPMs - 2003 Dodge Neon
Hi there - the best help going forward is to extract the problem codes turning on the Check Engine light. Most auto parts stores will read the problem codes for you for free. In a loss of power (https://www.yourmechanic.com/question/loss-of-power-while-driving) situation...

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 (855) 347-2779 · hi@yourmechanic.com