Mitsubishi ASC Service Required Warning: System Disabled

ASC Service Required means your Mitsubishi has switched off stability and traction control because something it relies on reported a fault. The causes run from a weak battery, which costs nothing to rule out, through a wheel speed sensor at around $20, a brake light switch that needs adjusting, or a steering angle sensor needing recalibration after an alignment. If you have a 2017 to 2018 Outlander, a 2018 Outlander Sport or a 2018 Eclipse Cross, check recall 18V-621 first.

What ASC Is

ASC is Mitsubishi’s stability control system. You will see it written two ways, sometimes in Mitsubishi’s own manuals: Active Stability Control and Active Skid Control. They are the same system.

It uses wheel speed, steering angle, yaw rate and sideways acceleration to work out whether the car is going where you are steering. When a wheel starts to slip it brakes that wheel and asks the engine computer to cut power. That last point explains one of the less obvious causes below: an engine fault can switch ASC off, because ASC cannot ask the engine to reduce power if the engine computer is reporting a fault of its own.

Is It Safe to Drive?

With only the ASC light on, your normal brakes and ABS still work. What you lose is stability control, traction control, brake assist, hill start assist and, on some models, the active limited slip function. The car will drive normally on dry roads but will not catch a skid for you, so drive gently in rain, snow or on loose surfaces until it is fixed.

If the ABS warning light is also on, ABS is disabled too. Leave extra stopping distance and get it looked at promptly. If the red brake warning light comes on, stop and check brake fluid before driving further.

ASC Service Required and the Car Will Not Start

This combination is extremely common and it is usually the battery. The ASC computer, the ABS pump motor and the data network that links the car’s computers all need stable voltage. When the battery sags during cranking, the ASC system logs a voltage fault and shows the warning, and the car fails to start for the same underlying reason.

On the 2007 Outlander, Mitsubishi’s low voltage code C2100 sets when voltage falls below about 9.7 volts, or below about 8.0 volts with the car stopped. Charge or jump the battery, then load test it. If the car starts and the warning clears after a few drive cycles, you have your answer.

The Causes, and How Each One Shows Up

Nobody publishes how often each cause occurs, so the order below follows Mitsubishi’s own diagnostic logic and runs from cheapest and most likely to most expensive. Code numbers are for the Lancer, Lancer Evolution, Outlander, Outlander Sport and ASX family unless stated. Read the warning about code numbers below before looking yours up.

1. Low battery or charging voltage

Codes: C2100 (voltage low), C2101 (voltage high, around 18 volts or more), C2116 (pump motor supply voltage). Covered in the no start section above. This is the first thing to rule out because it is free and it causes faults in several systems at once.

2. Wheel speed sensor

ASC needs all four wheel speeds to work out slip. If one sensor drops out, the whole system shuts down. Sensors sit at the wheels in road spray and salt, and the toothed ring they read from can rust or crack.

Codes: C100A, C1015, C1020, C102B (circuit, front left, front right, rear left, rear right); C1011, C101C, C1027, C1032 (signal); C1014, C101F, C102A, C1035 (cross check between sensors).

Before you buy a sensor, test it. Mitsubishi’s specifications for the sensor circuit are a current draw of 5.9 to 8.4 mA or 11.8 to 16.8 mA depending on the sensor, insulation resistance of 5 megohms or more, and 1 volt or less between the signal and ground terminals with the ignition on. A sensor that passes all of those is not your fault.

3. Brake light switch

ASC needs to know when you are braking. A switch that is misadjusted or failing sends the wrong signal. Code: C1000 (stop light switch circuit), sometimes with B1136 or P0703.

Mitsubishi’s dealer guidance for the 2011 and later Outlander Sport and RVR is to check the switch adjustment before replacing anything, and to confirm that both rear light assemblies are genuine Mitsubishi parts. Mitsubishi specifically names aftermarket TYC and Seanlty tail light assemblies as not covered under warranty in this context. If your tail lights have been replaced, check what brand they are.

4. Steering angle sensor that needs calibrating

ASC compares where you are steering against how the car is actually turning. If the sensor’s stored straight ahead position is wrong, the comparison fails. In most cases the sensor is fine and simply needs recalibrating.

Codes: C1219 (signal), C121A (neutral position not learned), C2205 (internal fault), U0126 and U0428 (communication). With C121A the ABS warning light flashes at a steady fast rate, about twice a second, which is a useful tell.

Mitsubishi requires calibration after a front wheel alignment, after the sensor is removed or replaced, and after the ABS hydraulic unit is replaced. Mitsubishi’s procedure is a two stage learn: the steering angle sensor first, then the neutral position inside the ABS and ASC system. Doing only the first stage is a common reason the light comes back.

5. An engine fault switching ASC off

This is the cause people miss. To control wheelspin, ASC asks the engine computer to reduce power. If the engine computer refuses because it has a fault of its own, ASC logs that and shuts down.

Codes: C121C (torque request rejected by the engine computer), U0401 (engine malfunction reported), U0100 (lost contact with the engine computer). Mitsubishi’s procedure for these is to check the engine for fault codes and fix those first. When the engine fault is fixed, the ASC code clears.

Owners often blame a dirty throttle body for this. The way it would happen is real, as described above, but we have not found a Mitsubishi source showing it is a common cause, so check the engine codes rather than cleaning the throttle body on a hunch.

6. A fault on the data network

The ASC computer, engine computer, steering sensor, body computer, all wheel drive computer and yaw sensor all talk over a shared data network. One corroded connector, or one module dropping off the network, takes ASC down even when every part is healthy.

Codes: C1290 (network timeout), U0001, U1003, U1073 (network shut down), and timeouts for individual modules: U0100 engine, U0101 transmission, U0114 all wheel drive, U0125 yaw and G sensor, U0141 body computer.

7. Yaw rate and G sensor

Codes: C1210, C1242 (forward and backward G), C123C (sideways G, or the sensor fitted at the wrong angle), C2204 (internal fault), C123A (calibration), C1392 and C1393 (calibration not completed). C123C specifically includes incorrect installation, and Mitsubishi warns that the sensor must not be dropped or knocked. It needs calibrating after replacement.

8. Mismatched tires

Code C123B means ASC has been intervening for too long. A tire with a different size or a lot less tread than the others makes one wheel look as if it is always slipping, so ASC keeps intervening until it times out. Check that all four tires are the same size and evenly worn.

9. The ABS hydraulic unit and ASC computer

These are combined in one assembly. Valve, pump motor and computer faults appear as codes such as C104B to C1067 (inlet and outlet valves), C1200 and C1204 (cut valves), C1073 (pump motor drive circuit) and C2200 (ASC computer). This is the expensive part, and it is the one most often blamed too early.

Before You Condemn the ABS Unit: Coding Faults

Some codes look like a failed module but are actually software or setup faults on a unit that is physically fine: C2203 (VIN not recorded), C2206 (coding needs to be redone), U1415 and U1417 (coding missing or invalid, including incorrect installation), U1195 and U1197 (coding not completed), C1707 and C1608 (implausible data). These are common after a used unit is fitted or after dealer software work, and they are fixed by coding, not by buying another unit.

Warning: the Same Code Means Different Things on Different Mitsubishis

Mitsubishi did not keep its ABS and ASC code numbers consistent across models. If you search a bare code online you can easily get the meaning for a different car. Some examples:

Code	Meaning on Lancer, Outlander, ASX family	Meaning elsewhere
C1200	Front left and rear right cut valve	Front right wheel speed sensor circuit
C1210	Forward and backward G sensor	Rear right wheel speed sensor circuit
C1073	Pump motor drive circuit	On the 2022 and later Outlander: vacuum sensor
U0101	Transmission (CVT) timeout on the Outlander	TC SST transmission timeout on the Lancer Evolution X

The 2022 and later Outlander uses an entirely different numbering scheme, shared with Nissan. The Mirage uses its own numbers for the wheel speed sensors (C1200 front right, C1205 front left, C1210 rear right, C1215 rear left). Always look a code up against your exact model and year.

The Order Mitsubishi Says to Diagnose In

Every Mitsubishi ASC fault procedure starts the same way, and it is the opposite of how most people approach it.

1. Check the data network first. Mitsubishi’s procedures warn that a network fault can produce misleading codes in other systems, so it is diagnosed before anything else.
2. Check the engine computer for its own codes. An engine fault can switch ASC off, as explained above.
3. Then work through the ASC codes, separating current faults from stored history.
4. The ABS hydraulic unit comes last. In the U0401 procedure it is step 4, and in the C121C procedure it is step 6, reached only after everything else is ruled out.

Skipping straight to the ABS unit is the most expensive mistake on this repair. It costs $399 to rebuild by mail and much more new, when the fault may be a corroded connector, a sensor, a switch adjustment or a calibration.

Free and Cheap Checks First

• Battery: load test it and confirm charging at idle.
• Recent alignment, steering or suspension work: have the steering angle sensor calibrated, both stages.
• Brake light switch: check the adjustment, then confirm the brake lights work. If the tail lights are aftermarket, note the brand.
• Tires: same size and similar tread on all four.
• Brake fluid level: low fluid sets C1009 on the 2007 Outlander and C105D on the 2022 and later Outlander.
• Connectors at the wheels: look for corrosion and chafed wiring at each wheel speed sensor.

How to Reset the ASC Light

The ASC light is not a reminder that you reset. It goes out when the fault is fixed, sometimes straight away and sometimes after a few drive cycles. Some codes are stored and need clearing with a scan tool after the repair. Disconnecting the battery may clear the light briefly, but if the fault is still there it comes straight back, and you lose the fault history that would have told you what was wrong.

Recalls and Service Bulletins

• Recall 18V-621 (Mitsubishi SR-18-008). 2017 to 2018 Outlander with adaptive cruise or electric parking brake, 2018 Outlander PHEV, 2018 Outlander Sport with forward collision mitigation, and 2018 Eclipse Cross. About 59,000 vehicles. Software in the ABS hydraulic unit can make it reset when the pump runs, which cancels ASC momentarily, and can also cancel adaptive cruise and automatic braking. Free software update at the dealer. Recall report.
• Recall 14V-564 (SR-14-010). 2007 to 2009 Outlander built December 2006 to August 2009. The brake light switch can fail. Replacement part 8614A049. A failed brake light switch is exactly what sets C1000. Recall document.
• Mitsubishi campaign SR-13-004. 2013 Outlander Sport and RVR built June to September 2012. Brake light switch plunger gap set incorrectly at the factory, so brake lights stay on or flicker. The fix adjusts the switch and clears the stored codes.
• TSB-20-35-001. Corrects Mitsubishi’s own wheel speed sensor diagnostic procedure for the 2014, 2015 and 2017 Mirage and 2017 Mirage G4. If a shop is using an older manual on these cars, the procedure was wrong. Bulletin.
• TSB-23-35-003. Corrects the warning light table for the 2022 and 2023 Outlander. Bulletin.
• TSB-23-35-004. Corrects the steering sensor calibration procedure for the i MiEV, and is the source of the alignment and two stage calibration requirement described above. Bulletin.

Check your VIN at nhtsa.gov/recalls.

What to do next: working Mitsubishi’s order with a tool

The diagnostic order above is Mitsubishi’s own, and it is the opposite of how most people approach this. Here is how to actually follow it, with the free steps first.

1. Load test the battery and check charging voltage. Free at most parts stores. On the 2007 Outlander, Mitsubishi’s C2100 sets below roughly 9.7 volts. If the car also will not start, this is almost certainly your whole problem.
2. Check the recall by VIN if you have a 2017 or 2018 Outlander, 2018 Outlander PHEV, 2018 Outlander Sport or 2018 Eclipse Cross. Campaign 18V-621 is a free software fix for a fault that cancels ASC.
3. Check tires and the brake light switch adjustment. Mismatched tire sizes set C123B, and a misadjusted switch sets C1000. Both are free to check.
4. Read the data network and engine module first, before the ASC codes. Mitsubishi’s procedures warn that a network fault produces misleading codes elsewhere, and an engine fault switches ASC off on its own through C121C.
5. Then read the ASC module and separate current faults from stored history. Stored codes on their own usually mean an intermittent that has already cleared.
6. Put live wheel speeds from all four wheels on screen and drive slowly. One wheel reading zero or jumping around while the others track together isolates the sensor without removing anything.
7. If the car had an alignment, steering or suspension work recently, run the steering angle calibration. Mitsubishi requires a two stage learn, the sensor and then the neutral position inside the ASC system. Doing only the first stage is a common reason the light comes back.
8. Clear the codes and drive it. Watch what returns.

The YOUCANIC UCAN-II Pro reads the Mitsubishi ABS and ASC modules and shows live wheel speed on all four wheels, which covers steps four to six. It is available as a seven day rental for a one off job. For the calibration in step seven, check coverage for your exact model and year first, so email support with your VIN before ordering.

When you do not need a scan tool for this

Steps one to three need no tool at all, and between them they account for a large share of these warnings. A weak battery, an open recall, a mismatched tire and a brake light switch out of adjustment are all free to find and three of the four are free to fix.

Do those before spending anything. If the warning clears, you are done.

What It Costs

Repair	Typical cost
Battery charge, sensor calibration, switch adjustment	No cost for parts
Wheel speed sensor, part only (2011 Outlander, RockAuto)	About $18 to $90 front, $6 to $171 rear
Wheel speed sensor, fitted (Outlander, RepairPal estimate)	About $250 to $609 for 2011 to 2015 models
ABS unit and ASC computer, mail in rebuild (Lancer and Outlander)	$399 plus shipping
ABS unit and ASC computer, new	Quoted by one rebuilder at $2,307 list price; not confirmed with a dealer

Part prices vary a lot by brand and even for the same part across different listings, so compare by part number. No published labor time exists for this job on Mitsubishis, so treat shop quotes with that in mind.

Where a Scan Tool Fits In

Most generic OBD2 code readers only talk to the engine computer, so they show no codes at all on a car with a live ASC fault. That is why so many owners are told the scan came back clean. Reading the ASC, ABS and steering sensor codes, watching live wheel speeds, and running the steering angle and G sensor calibrations all need a tool that reaches those systems. Mitsubishi’s own dealer tool is the M.U.T.-III.

The YOUCANIC UCAN-II Pro reads Mitsubishi ABS and ASC codes and shows live wheel speed on all four wheels, which covers most of the diagnosis in this guide. For the calibration routines, check the scanner’s coverage list for your exact model and year before relying on it.

When to Hand It Over

• The ABS warning light is on as well, and you cannot find the cause quickly. Braking is affected, so do not leave it.
• Codes point at the ABS hydraulic unit and the network, engine and sensor checks all pass.
• Coding faults are present, which need dealer level software to correct.
• You need the yaw and G sensor or hydraulic unit calibrations and do not have a tool that performs them.

Frequently Asked Questions

What does ASC Service Required mean on a Mitsubishi?

It means the stability control system found a fault and switched itself off. Normal braking still works, but stability and traction control are not available.

Can a weak battery cause the ASC warning?

Yes. Low voltage is a common trigger. Test the battery and charging system before you replace any sensors.

Will the ASC warning clear on its own?

It can go out after a restart if the fault was brief, but the code stays stored. Read the codes so you know which sensor or circuit set it.

Related guides: Fixing Mitsubishi DTCs: Easy Code Reading Clearing Guide · ABS Sensor Replacement Guide Mitsubishi Mirage

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