Harley-Davidson trouble codes: complete list with explanations
Is the check engine light on your Harley on? Here you'll find all 360+ trouble codes (P, B, C and U) with a plain-English explanation, and how to read and clear them yourself, without a diagnostic tool.
Search by code (P0562) or by a word (turn signal, battery, ABS).
What is a Harley trouble code (DTC)?
A trouble code, officially a Diagnostic Trouble Code (DTC), is a code your Harley's electronics store when a sensor, switch or module measures something that isn't right. As soon as the engine control module (ECM) sees a fault, the check engine light comes on for many faults.
The first letter tells you which system the fault is in:
P Engine, fuel and ignition
B Electrics, lighting, security, radio
C Chassis: ABS and brakes
U Communication between modules
A code can be current (the fault is there now) or historic (the fault happened and was stored). On many models the check engine light first comes on for a few seconds as a bulb check when you switch on the ignition. If it then stays on for about another 8 seconds, a historic code is stored. If it stays on, there is a current fault.
Reading Harley trouble codes without a diagnostic tool
How you read the codes depends on the model year and the type of engine management. See below which method applies to your bike.
Approx. 2001 to 2013 · Twin Cam with digital odometer
Reading via the trip button (odometer)
Set the run/stop switch to RUN and the ignition OFF.
Hold the trip button (trip meter reset) pressed.
Switch the ignition ON and release the button. The display shows diag.
Press the button briefly. You now see a row of letters, for example PSSPt. The flashing letter is selected.
Press briefly to move to the next module: P = engine (ECM/ICM), S = security/turn signals (TSM/TSSM/HFSM), SP = speedometer, T = tachometer.
Hold the button for 5 seconds to show the codes for that module. If it shows none, there are no codes. No rsp means the module doesn't respond or isn't fitted.
Several codes? Press briefly to see the next code. Write everything down before you clear anything.
Switch the ignition off to leave the diagnostic menu.
Touring from 2014 · Softail from 2018 · Milwaukee-Eight
Reading on newer models
The principle is the same, but on Touring models from 2014 you use the trip/toggle switch on the left handlebar control instead of a button on the gauge. On the display the modules often have a longer name:
ECM engine
BCM lighting, starter, switches
ABS anti-lock braking system
SPDO speedometer / instruments
RAD radio / infotainment
AMP amplifier
The exact menu order differs by model and year. If it doesn't work, check the service manual (Electrical Diagnostic Manual) for your model.
Approx. 1995 to 2001 · Magneti Marelli fuel injection
Reading via the flashing check engine light
Switch the ignition on and off three times and leave it on the fourth time.
The check engine light first flashes quickly, stops and then starts flashing slowly.
Count the slow flashes: that is the first digit. After a pause comes the second digit. Three flashes, pause, two flashes is code 32.
If there are more codes, a series of quick flashes follows and then the next code. Look up the meaning in the table of old flash codes.
Older carburetted Harley? Carburetted Evolution models don't store trouble codes. Carburetted Twin Cams (approx. 1999-2006) have an ignition control module (ICM) that can store a limited number of P codes, which you read via the trip button.
Clearing (resetting) Harley trouble codes
Read the codes as described above and write them down first.
While a code is shown on the display: hold the trip button for more than 5 seconds until clear appears. All codes for that module are now cleared.
Repeat this for every module that has codes stored.
Switch the ignition off, start the engine and read again. If a code comes back, the fault is still current and you need to fix the cause.
Please note: clearing a code doesn't fix the fault. And if you're buying a used Harley, ask whether you can read the codes yourself. Historic codes tell you a lot about the bike's history, especially with a bike from America. Also read what a VIN check and CARFAX tell you.
The most common Harley trouble codes explained
The codes below come up most often in practice. For each code you can read what it means, what usually causes it and whether you can still ride.
P0562 / P0563: battery voltage too low or too high
The ECM measures a supply voltage outside the normal range. P0562 is too low, P0563 too high. This is one of the most common Harley codes, and often the cause of a whole row of other (U) codes.
Common causes
Weak or old battery, especially after a winter standing still
Loose or corroded battery terminals or ground cable
Faulty voltage regulator or stator (P0563 = regulator charging too high)
Lots of extra consumers (lighting, audio) on a limited charging output
What can you do?
Measure the battery with a multimeter: at rest a full battery should be around 12.6 to 12.8 V, with the engine running at raised revs about 13.8 to 14.5 V. If you're below or above that, first check the terminals and ground, then the regulator and stator. Always fix this first: many communication codes disappear by themselves once the voltage is right again.
Caution. Riding home gently is usually possible, but with low charging voltage you risk the engine stalling on the way.
P1353 / P1356: no combustion front or rear cylinder
Many Twin Cam models use the spark plug (ion sensing) to check whether combustion actually takes place in the cylinder. If the ECM sees no combustion, you get P1353 (front) or P1356 (rear). P1357/P1358 means it happens now and then.
Common causes
Worn or wrong spark plugs (note: use resistor plugs)
Damaged or wrong plug leads, for example non-resistor race leads
Faulty ignition coil or injector
High compression or aftermarket parts that give false codes at high revs
What can you do?
Start with the cheap things: check the spark plugs and plug leads and replace them with the right type if needed. Clear the code and see if it comes back. If it only returns above a certain rpm while the engine runs well, it can be a false reading. If the engine really runs on one cylinder, have it checked.
Caution. If the engine runs normally, it's often a measuring issue. If it stutters or runs on one cylinder, don't ride further than necessary.
The O2 sensors in the exhaust measure how much oxygen is in the exhaust gas. A low voltage means the engine runs lean (too little fuel), a high voltage that it runs rich. P0134/P0154 means the sensor gives no usable signal at all.
Common causes
Different exhaust or open air cleaner without an adjusted map, very common on bikes from America
Air leaks from leaking intake seals or a leaking exhaust gasket
Dirty or faulty O2 sensor
Broken wiring, often burnt against the exhaust
What can you do?
First check whether the bike has aftermarket parts. A Screamin' Eagle air cleaner or a different exhaust without a new map is a classic cause. Then look for leaks at the intake and exhaust. With an imported bike, also keep the registration inspection in mind: the exhaust must meet the noise limits.
Usually harmless. Riding on is usually fine, but an engine that runs lean for a long time runs hotter. Have the map sorted out.
P0371 / P0373 / P0374: crankshaft position sensor (CKP)
The crankshaft sensor tells the ECM how fast and in which position the crankshaft is turning. Without a good signal the engine doesn't know when to fire and inject.
Common causes
Metal particles on the magnetic tip of the sensor
Loose, dirty or corroded connector
Damaged cable
Faulty sensor
What can you do?
Take the sensor out and clean the tip, check the connector and the cable. If the code comes back, replace the sensor. It's an affordable part.
Don't ride with it. A bike with this problem can stall without warning or fail to start. Better not take it on the road.
P1510 / P1511 / P2135 / P2138: electronic throttle and limp mode
Models with electronic throttle (throttle-by-wire, on Touring from 2008) switch to limp mode when the sensors in the twist grip or the throttle body don't agree. The engine then has little power or stays at idle.
Common causes
Dirt or wear in the throttle body
Faulty twist grip sensor (TGS) or throttle position sensor (TPS)
Poor connector contact
Low battery voltage while starting
What can you do?
First check the battery voltage and the connectors at the throttle body and twist grip. P2176 often appears after replacing or cleaning the throttle body or the ECM: the closed throttle position then needs to be relearned.
Don't ride with it. In limp mode you have little power. Not something you want when merging onto the motorway.
B2255 and other 'switch stuck' codes: a switch is stuck
The modules on your Harley (ECM, instruments, security, radio) talk to each other via a data bus. If a module gets no data or wrong data, a U code follows.
Common causes
Low battery voltage or starting with a weak battery (the most common cause)
Loose connector, for example behind the headlight or the instrument panel
Fitted accessories or a different radio/head unit disturbing the data bus
Damaged wiring
What can you do?
First check whether there is also a voltage code (P0562) and fix that. Then clear all codes. A one-off U code after a flat battery is usually historic and doesn't come back. After fitting a new head unit or other accessories: check that everything is connected according to the manual.
Caution. It depends on which module drops out. If the gauges and lights work normally, you can usually ride on calmly.
The module that controls the turn signals measures an abnormal current: open circuit, short circuit or overload.
Common causes
LED turn signals without the right resistor or module (they draw much less current)
Faulty bulb or loose connector
Modified lighting, for example when converting for Europe
What can you do?
First check that all turn signals work. If you've fitted LEDs, use the right resistors or a suitable module.
Usually harmless. Riding safely is possible as long as your turn signals visibly work. Otherwise fix it first: without working turn signals you also won't pass the inspection.
P1009 / P1010 / B1143-B1145 / B2176: security and alarm
The security system (Smart Security System / H-DSSS) doesn't recognise the key fob, or the antenna has a fault. P1009 means the ECM isn't delivering fuel because the password is wrong.
Common causes
Flat battery in the key fob
Fault or loose connector at the security antenna
Replaced ECM or security module that hasn't been paired
Bike bought without a (working) fob
What can you do?
First replace the battery in the fob. If that doesn't work, on many models the bike can be unlocked temporarily with the personal identification number (PIN) via the turn signal buttons. If you're buying a used Harley, always ask for the fob and the PIN.
Don't ride with it. Usually the engine won't even start. Don't force it, check the fob and antenna first.
The ABS module gets no signal or an unreliable signal from the front or rear wheel speed sensor. The ABS switches itself off and the ABS light comes on.
Common causes
Dirty or damaged encoder ring at the wheel
Wrong gap between sensor and encoder, often after fitting different wheels
Damaged cable or connector
Different tyre size (C1029: too much difference front/rear)
What can you do?
If you've just fitted different wheels or tyres, check that the encoder ring and the spacers are seated correctly. Clean the sensor and check the cable.
Caution. Your brakes still work, but without ABS. Brake carefully, especially in the wet, and have it fixed soon.
Complete list of all Harley-Davidson trouble codes
Below are all 368 codes, grouped by system. The descriptions use the original terms from the Harley service documentation, so you can easily search further. Use the search bar at the top to jump straight to your code.
Internal ECM fault (RAM/ROM/EEPROM) - ECM usually replaced
56
Crankshaft/camshaft sensor synchronisation error
The numbering can differ slightly by model and year. If in doubt, check the service manual for your bike.
Frequently asked questions about Harley trouble codes
How do I read my Harley's trouble codes without a diagnostic tool?
On most Harleys with a digital odometer: set the run/stop switch to RUN and the ignition off. Hold the trip button, switch the ignition on and release the button. The display shows 'diag'. Select the module with a short press (P = engine, S = security, SP = speedometer, T = tachometer) and hold the button for 5 seconds to see the codes. On Magneti Marelli fuel-injected bikes from approx. 1995 to 2001 you read the codes from the flashing check engine light.
How do I clear trouble codes on a Harley-Davidson?
Make sure the code is shown on the display and hold the trip button for more than 5 seconds until 'clear' appears. That clears all codes for that module. Switch the ignition off, start the engine and read again. If the code comes back, the fault is still current.
What is the difference between a current and a historic trouble code?
A current code means the fault is present now. A historic code is stored from an earlier fault that is now gone, for example when the battery was flat. Historic codes clear themselves after a number of start cycles without the fault. You can tell the difference by clearing, starting and reading again.
My check engine light is on. Can I still ride?
That depends on the code. A trip button or radio code is harmless; a crankshaft sensor (P0373/P0374) or electronic throttle in limp mode (P1510) is not. Read the code first and look it up in the list above. If in doubt, don't ride further than necessary.
Do older carburetted Harleys have trouble codes too?
Carburetted Evolution models have no trouble code memory. Carburetted Twin Cam models (approx. 1999 to 2006) have an ignition control module (ICM) that can store a limited number of P codes. You read those the same way via the trip button, provided the bike has a digital odometer.
Which diagnostic tool do I need for a Harley?
For most codes you don't need a tool: reading and clearing works via the trip button. If you want to see live sensor data or relearn things, you need diagnostic software or a tuner that works with the Harley protocol. A standard OBD2 car scanner usually doesn't work without a special adapter and software.
Why should I read the trouble codes when buying a used Harley?
Historic codes show which faults the bike has had in the past, even if the light is off now. Be extra alert if all modules show 'none' while the seller worked on the bike just before: the codes may have just been cleared. So when viewing a bike, always ask whether you can read the codes yourself.
Stuck, or looking for a Harley from America?
Send your code and a short description on WhatsApp and I'll think it through with you. I also sell Harleys from all model years that I've inspected and picked up myself in America, with a walkaround and start-up video of every bike.
Sources: Harley-Davidson service and diagnostic information as published by Harley-Davidson dealers and ThunderMax. This list has been compiled with care, but it does not replace the official service manual. If you're unsure about the safety of your bike, have it checked by a specialist.
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