What is Limp Mode? – Causes & What to Do

Picture this: you are driving along when, out of the blue, your car’s transmission starts acting up. The “check engine” light comes on, telling you that there is a problem. At the same time, your car’s transmission automatically shifts into second or third gear and stays there.

Limited to one gear and 30-45 mph, you know there is a serious problem with your car’s transmission and you have to get your car to either your dealer or transmission repair shop to have the problem diagnosed and repaired.

Naturally, the first questions that go through your head are: Why did this happen? How severe is it? and How much will it cost to fix?

We know a good transmission shop in your area.

In This Guide

What Causes Limp Mode?

Since the early 1980s, computers have been responsible for monitoring and controlling systems in automobiles. At first, the computer was used primarily for emissions control and fuel economy, but within a few years, many more systems were computer controlled included anti-lock braking, airbags, climate control and handling.

Today, nearly every system in your vehicle is operated by the computer – including the transmission’s line pressure, shift timing, sequence and feel. The vehicle speed sensor provides input to help control ABS, fuel mixture, fuel injection and transmission operation. The manifold absolute pressure (MAP) sensor and throttle position sensor (TPS) provide the engine’s load information which is used to manage the shift and downshifting in the transmission when you’re driving up an incline or you’ve put the pedal to the metal.

“Fail Code” conditions or “Limp Mode” occurs when there is a problem with the logic of a vehicle’s computer. When the signal value sent by a sensor to the computer is not within a pre-programmed range specified by the manufacturer, it will switch to “secondary” programming. These procedures are designed to protect the transmission from further damage that could be caused by the signal error.

As long as the computer is receiving signals from the MAP, TPS, vehicle speed and other sensors that fall within their “normal” ranges based on the current conditions, the transmission will operate normally. However, as mentioned above, if it receives a signal that is outside of the expected range, it will switch to secondary/emergency operation.

The exact measures taken in secondary operation is determined by the computer’s logic as programmed by the manufacturer and depends on how far outside the acceptable range the signal is (if there is any signal at all). It might react differently when the value is higher than the highest parameter than it does when the value is lower than the lowest allowable value.

Limp Mode’s Protective Actions

Check Engine Light - Limp Mode

If the signal value wasn’t far enough outside of the range to indicate a mechanical failure, the first thing the computer will do is turn the check engine light on to alert the driver that they should have the vehicle checked out using a code reader/diagnostic scanner to see if there are any “soft codes” listed. Soft codes can indicate that a low priority sensor has malfunctioned or is starting to break down. If the light goes away after restarting your car, it could mean that the sensor only failed once due to a loose connection or it could be a sign that its condition is getting worse. Critical functionality is typically unaffected by this kind of problem, but if the issue isn’t resolved, it can negatively impact the performance or fuel efficiency of the vehicle.

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Now, if the signal value from a high priority sensor (necessary for critical functions) is dangerously far out of the acceptable operating range, the computer switches over to secondary “survival” mode. This is known as a “hard code”. In this mode, the computer shuts off the electronic shift solenoids. This disables the transmission’s ability to shift gears and causes it to default to single usable gear – usually second or third. In addition, the pressure in the transmission’s fluid lines is set to high in order to protect the bands and clutches from being damaged. The signals that control the line pressure are set to “full on” to prevent the clutch pack from a slipping dangerously.

All of these changes result in the previously described “Limp Mode”. Instead of leaving you stranded with a broken down vehicle, it enables the vehicle to limp home or to the nearest service center for repairs while reducing the risk of doing further damage.

Example

For example, one of situations that would cause a transmission to go into limp mode is if the cable harness going to the transmission is damaged or detached. In this case, the computer would sense that it lost communication with the transmission, but since the harness is detached, the command to go into limp mode cannot make it to the transmission. However, with no power supplied to the solenoids, the line pressure is set to high and the transmission is stuck in 2nd or 3rd gear – the same effect the limp mode command would have.

How the Computer Determines That a Sensor is Incorrect

Say, for example, that the computer receives a signal from the Throttle Position Sensor (TPS) stating that the pedal is to the metal when the throttle is actually closed. It would spot this error when it compared this status with the vehicle speed sensor, which would be signaling low or no speed. As soon as it sees this discrepancy, the computer will command the transmission to go into limp mode and turn the check engine light on. A signal value by itself can’t always be classified as an error, but when analyzed with other sensor outputs, the computer can easily figure out if there is a problem.

Fault Code Diagnostic Scanner

The fault code of the sensor causing the error is recorded by the computer. A mechanic can use a diagnostic scanner or code reader to find the recorded codes and then look them up in a table from the manufacturer to determine which sensor, and therefore which system is the source of the malfunction. Many scanners are pre-programmed with these tables and return more information than just the codes.

For example, the diagnostic scanner could return the code “35”, which indicates that the problem has to do with the transmission fluid temperature sensor. The abnormal values that were recorded and the “normal” range for the sensor could also be provided to the mechanic.

It is recommended to have a vehicle’s computer scanned regularly for fault codes – especially if the check engine light is on. This is done by most service centers during routine tune-ups.

What You Should Do

If your transmission is in limp mode, your transmission has a problem and you should get it fixed as soon as possible. Here is what you should do:

  • Do not panic! Limp mode is specifically designed to limit further damage and allow you to get your car to a service center
  • If possible, drive directly to a service center
  • Otherwise, drive home and call a service center to have your vehicle towed
  • If you do not feel comfortable driving at a limited speed, pull off the road where it is safe to do so and call for a tow
  • It is advised that you do not continue to drive a vehicle in limp mode as it is unsafe and can cause further damage to your vehicle

Questions to Ask Yourself

Once your vehicle is safely in the service area, it is time to answer a few questions that will help diagnose the problem:

  • How fast were you driving and how long had you been driving when the problem occurred?
  • Did any lights on the dash come on? Did they come on when you started the car or after driving a while? Did they stay on?
  • What repairs or maintenance has been done to the vehicle in the last month?
  • Have you noticed any signs of a problem recently (noises, behaviors, leaks, etc.)?

Get a Diagnosis

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26 thoughts on “What is Limp Mode? – Causes & What to Do

  1. When I put my 96 premio in drive or reverse it only maintains for less than a minute and goes idle. When I switch off and restart it the same happens and that’s how I managed to reach home. I’ve had the torque converter and pump changed but same results. Could it be the computer?

    • Hey chavis. I have a 2008 Ford escape with the same problem. I can put it in drive and reverse but after awhile it loses the driving force, sort of like it goes into neutral. I retrieved codes about the TCC solenoid. So I replaced it. But still the same problem but no codes are being set. I was wondering if you were able to figure out the problem. Thank you.

  2. Fred it may be the TPMS sensor, often this will throttle down the gearing in the transmission and often applies to the rear differential. You can try opening the glove box and shifting into overdrive.

  3. I have a 2007 ford lariat f150 5.4 triton, just satrted “Thunking when it looks to be a gear changing around the 40 km mark the RPM goes up but the truck doesent accelerate then when it does it thunks n jolts w acceleration.

  4. I have a 1992 Honda Civic and today changed throttle cable, and throttle body. The car will not rev beyond 1600 rpm and someone mentioned TPS limp mode. Do you believe this is limp/TPS limp or is there another issue?

  5. I have a 1997 acura cl 3.0 vtech wih tranny problems. At idle when attempting to go into gear, the idle goes really low but it fails to catch the gear. And oddly, the idle decreased when placed in neutral and it acts like it wants to go into a gear then? Opinion on it?

  6. I have a 2000 nissan sentra and thr o/d light blinks 16 times when i turn it on and its seems to be stuck in one gear and doesnt shift but it works perfectly every once in a while. is tbat my transmission or a prblem with the solenoid? please help

  7. I have an Audi a4 automatic 2003 when I put it in drive it pops out off gear when it reach 30 to 35 mph and then stalls. The engin revs but doesn’t move. The only gear that works is reverse. Can this be happening become of a bad ecu? I really hope it’s not the transmission. I unplug the tcm and battery for 10 minutes and the car is able to drive forward again until it reaches 30 to 35 mph then the car just pops out gear and stalls again. The car does not turn off when this happens, it just revs with no excelartion. If any one can help I would really appreciate it..

  8. I have a 2006 ford f250 super duty, it has the 6.0 motor. recently changed some seals on the upper intake and oil pressure housing. once I drove it a week, my truck now goes into limp mode. my turbo builds boost but have no take off power on the highway any suggestions? already checked some sensor and cleaned them but still no luck.

  9. I have a mitsubishi lancer 1997 make 1500 cc automatic. When i start the engine it sounds well but I shift the gear to D mode it just shuts down. I have tried many mechanics for the last one year but no one seems to crack it. how can i make that vehicle to move again?

  10. I have a 94 jeep grand cherokee. And it’s in limp mode. It always felt like it started off in second. Could it be a shift solenoid? Or do I need a whole new tranny?

  11. I have a 1992 mercury tracer it fills like my tranny is slipping or just fell out of gear if I stop turn off the vehicle and start it again put it in drive and give it gas it drives fine until I come to a stop or let off the gas pdeal wen I go to take off the rpm s go up but no movement it will happen of I let off the gas at forty to coast wen I press the gas again it just raises the rpm like it ain’t grabbing the gear or somethig

    • Car: Pontiac grand am se v6 4.3l

      Obd scan codes:

      P0300: misfire on one or more cylinders
      P0128: coolant temp is always low
      P1133: heated oxygen sensor bank #1 sensor #1 insufficient switching
      P0036: (oxygen sensor) heater condition-check repair resource for sensor location identification
      P0171: fuel trim bank one condition

      How the car acts when driven:

      Motor runs and idleds fine no backfiring or problems other then the EGR valve to the manafold was causeing a vac leak. I had fixed it with a replacement part.

      My automatic transmission without over drive will only let me use second gear. The rpms in second with accelerator fully to the floor it limited to 2500 rpms at a dead stop till I get to about 40. When I use reverse I can break the tires loose. When in drive it uses second gear at first till I get to 40mph then it shifts to 3rd and slips all th way to max rpms. When I slam multiple times on the gas going already 50 the car maxs out on rpms then throws me back in second gear I believe with the pedal to the floor.

  12. I have a 2001 Toyota hi lux and when I stop at the lights and go to take off the engine light comes on and the car goes into limp mode I have to pull over and turn the car of and then it starts again and I can drive it until I stop at a mother set of lights and it does it again, can any one help the macanic has had it for two days and carnt finger ot out and it’s a diesel manual and it is at a diesel macanic, it is dangerous because it happens at all the enter section.

  13. I have an 02 bmw 330i, it went in limp mode at around 35 mph, so I serviced the tranny, replaced my maf sensor, and still in limp mode. Could this just be a problem with resetting the computer?

    • we have the same problem with our BMW and cant find the problem after spending over 20 000.00 on the vehicle
      pls let me know if you solved yours

    • Hi, same issue with limp mode in 2004 320i, very low ks, just paid $$$ to have 2 x Spd sensors replaced & within 6 weeks limp mode again but bmw mechanic saying it’s another sensor!!! in the tranny!!!
      Can I just turn computer off that triggers limp mode as mech saying auto is fine,
      Thanks

  14. I have an 04 ford xr6 and while driving the car lost all gears but 1 I couldnt change to any other gear there was no lights on the dash could this be in limp mode or is the trans stuffed? It is a trick trans.

  15. I had a mechanic (whom I trust) look at my 2005 Ford Expedition for an A/C problem I was having. He found the problem to be an electrical issue and the source was probably a corroded bulkhead connector, etc. Instead of trying to take parts out, trace wires, etc, he decided it would be easier and just as effective to simply make a homemade jumper at the Compressor Clutch Relay. This worked to fix the A/C issue. However, about 10 minutes down the road, my SUV suddenly went into Limited Power (Limp) mode, the O/D dash light started blinking repeatedly, check engine dash light came on, and I couldn’t accelerate past about 30-45 mph. I turned around, took the truck back to the mechanic, we took off the jumper, and the truck stayed in Limp mode. We checked/cleared the engine codes, nothing changed. We’re thinking that we possibly fried something. Is it possible we simply fried the Compressor Clutch Relay? Would that cause Limp mode? Or did we possibly fry a computer component?

  16. I sheared the cooling fan wires completely apart,and the 05 f-350 went into the limp mode. I let the truck cool down,and made a new wire harness. I resumed driving about 100 miles to where I was going and no problems, about two hours later on my return trip, the truck just stopped running completely. Got out and checked the engine and the wires had come apart on the cooling fan again, so this time I pulled the truck the 23 miles home, then I redid the harness avsin, and had juice to everything but the ignition, it was a fuse, starts now, but won’t shift up, it actually locks the reared up when it trays to shift. I’m stumped, any thoughts on this anybody?

  17. I have a 2005 GMC Envoy with 207,000 miles on it. Yesterday while taking a turn and slowing down the car seemed to surge a little and since then while accelerating the engine is revving high but with considerably lower power and low speed. No dash lights have come on. The engine noise has become a ‘little’ whiny since today morning.
    Can someone please suggest what could be wrong here?

  18. My 2015 Dodge Durango went into limp mode when passing on highway — pulled over turned off the engine and restarted. No further problem until a couple of months later went into limp mode pulling out of day camp parking lot — 2 four year old grandchildren yelling out in the back “What is wrong with the car?’
    Brought the car (3,200 miles) to dealer — dealer said computer showed no problem; therefore, no problem. Really? left car at dealer and said I would not drive with grandkids in car until he found the problem — would he risk driving an unsafe car with this family members?

    • I have a 2008 Kia Amante. Two weeks ago, I made appt with my trusted RadAir due to car in “limp mode”. Check engine light on. RPMs would not go above 2. Slowly could increase to 60MPH. The morning of appt, my car accelerated properly, but still had diagnostic testing for
      check engine sensor. RadAir said no code showed on computer. Paid $100 for test. Car ran fine until today. Car went into limp mode again with engine light on. Even though diagnostic testing reveal no codes, shouldn’t the car be checked to rule out what caused the limp mode?
      Can an automatic car starter contribute to this problem even if it is working fine and is less than a year old. Please help.

  19. I have a 04 chevy trailblazer, I have first and reverse, I can manually shift into second. When it should shift into third it down shifts back to first. Before all this happen I was sitting and it was idling and the reduce engine power light came on. I shut it down and it was fine drove it home. Then this happened any idea what it could be. We was thing selinod, but now think maybe clutches for 3

  20. I have a 2002 honda civic and all of a sudden yesterday while we were drivinh it the transmission just acted like i had put it in neutral, i can cut tbe car off and start it back up and it will do fine for a mile maybe two then same thing happens again, and again can shut car off for just bout 10 seconds start it back and go again, what is wrong?

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