Which engine do you have? The locations below are confirmed on the DD13, which is the engine in the photographs. The DD15 is built differently and several sensors sit in different places on it; the DD16 shares the DD15 layout. Check your engine data plate before you start looking.
- Common Rail Fuel injectors (under valve cover center of cylinder head)
- Fuel Rail Pressure Sensor (attached to fuel rail towards front of engine)
- Supply Fuel Temp Sensor (located on driver side rear of engine)
- Camshaft position sensor (CMP) (located at the back of engine driver side cylinder head)
- Crankshaft position sensor (CKP) (located at back of engine near bottom of bellhousing)
- Engine Oil pressure sensor (driver side of engine block at front)
- Engine Oil Temperature Sensor (driver side of engine block at front)
- Turbo Speed Sensor (center of turbocharger housing)
- Oil Separator Speed Sensor (above Air Fuel ration Sensor in exhaust)
- Coolant Inlet Temperature Sensor (driver side of engine block at front)
- Coolant Outlet Temperature Sensor (located at front of engine at EGR Cooler)
- EGR Delta P Sensor (top front of engine)
- Intake Manifold Pressure Sensor (driver side of intake manifold at front of engine)
- Fuel Compensation Pressure Sensor (attached to front of Electronic Dosing Valve)
- Fuel Doser Line Pressure Sensor (attached to rear of Electronic Dosing Valve)
- Intake Manifold Temperature Sensor (driver side middle of intake manifold)
- LPPO Fuel Pressure Sensor (next to fuel filter housing)
Opposite side of Detroit DD13 EPA10 Engine
4. Camshaft Position Sensor (CMP)
Monitors the exact rotational position and timing of the camshaft relative to the position of the crankshaft to identify which specific cylinder is on its compression stroke. The MCM pairs this synchronization data with inputs from the crankshaft sensor to determine exact top dead center (TDC), allowing the computer to energize the high-pressure fuel injectors in the correct firing order. Sensor faults typically cause long cranking times, intermittent engine stalling, or a crank-no-start condition if the computer cannot determine cylinder positions accurately.
Where it is. The camshaft position sensor is located on the driver’s side of the cylinder head at the back of the engine. It is screwed vertically directly into the upper rear quadrant of the cylinder head, positioned just below the valve cover rail and right above the main flywheel housing junction. Look for a stepped plastic cylindrical probe roughly the length of a thumb, with a black 3-pin electrical connector.
Getting at it. Replacement is a straightforward 15-minute driveway job and no brackets, fuel lines, or intake pipes need to come off to change it, though you will be working near the rear fire wall area. You will only need an 8mm or E-8 Torx socket with a small extension and a ratchet to remove the single small hold-down bolt and pull the sensor vertically out of its bore.
Codes: SPN 723 with FMI 2 or 8 indicates an erratic, missing, or un-synchronized camshaft position signal.
Fitting it. This sensor uses a rubber barrel O-ring to seal out engine oil from the top-end gear train. Never install the sensor completely dry or use RTV silicone or PTFE tape on the plastic body; instead, apply a clean smear of fresh engine oil to the rubber O-ring to prevent it from tearing or binding when you push it into the head. When installing the small 8mm hold-down bolt, tighten it firmly with a small hand-driver only as over-torquing can easily snap the small bolt shank off inside the cylinder head casting.
How it typically fails. Sitting at the very back top-deck of the cylinder head exposes this sensor to intense thermal soaking every time the engine is shut down. Over hundreds of thousands of miles, this extreme heat cycling makes the plastic sensor body brittle, leading to hairline cracks that allow engine oil to short out the internal magnetic pickup coil. Additionally, if the internal O-ring bakes completely solid, the plastic mounting flange will snap clean off if you attempt to pry it upward with a screwdriver; always twist the sensor back and forth with pliers first to break the baked-on seal before pulling the sensor out of the cylinder head.
5. Crankshaft Position Sensor (CKP)
Tracks the exact rotational speed and position of the crankshaft by reading a machined tone ring on the engine flywheel. The MCM relies on this primary timing input to calculate engine RPM, determine the correct injection timing, and synchronize fuel delivery during startup and operation. A total sensor failure will trigger an extended crank-no-start condition or cause the engine to cut out completely while driving.
Where it is. The crankshaft position sensor is located at the lower rear quadrant of the engine on the driver’s side. It is bolted directly into the flywheel bell housing wrapper near the bottom edge. Because it is positioned at the back of the block, it sits below the main chassis frame rail line and is completely hidden out of sight from a top-down or straight-on engine view. Look for a cylindrical plastic and metal probe roughly the length of an index finger, featuring a short pigtail wiring harness that hangs down and terminates in a black 2-pin locking connector.
Getting at it. Replacement is an easy 10-to-15-minute driveway job, but the sensor must be accessed from underneath the truck by crawling beneath the transmission bell housing area. No structural brackets or engine components need to come off to change it, though road grease and dirt must be wiped away from the mounting area first. You will only need an 8mm or E-8 Torx socket with a small ratchet to remove the single hold-down bolt and slide the sensor straight out of its bore.
Codes: SPN 636 with FMI 2 or 8 indicates an erratic, missing, or out-of-sync crankshaft timing signal.
Fitting it. This sensor relies on a rubber barrel O-ring to seal its mounting hole, so never install the sensor completely dry or use RTV silicone or PTFE thread sealants on the body; instead, coat the rubber O-ring in a thin film of clean engine oil so it slides smoothly into the bore without twisting or shearing. When tightening the small 8mm mounting bolt into the iron flywheel housing, hand-tighten it firmly with a hand-driver to avoid snapping off the small bolt.
How it typically fails. Because the sensor tip is highly magnetic and exposed to the inside of the bell housing, it attracts wear debris. Over time, micro-fine metallic clutch dust and metal shavings from starter gear engagement mix with engine oil vapor to coat the sensor face in a thick, sludge-like paste. This metallic blanket dampens the sensor’s magnetic field, causing it to drop pulses at cranking speeds, which leads to intermittent long crank or even no-start conditions.
6. Engine Oil Pressure Sensor
Monitors the lubrication oil pressure within the engine’ lubrication system. The MCM relies on this data to ensure the engine remains properly lubricated during operation, using the input to drive the dashboard gauge, trigger low-pressure warning lights, or command an emergency automatic engine shutdown protocol if oil pressure drops below a minimum allowable threshold. Sensor faults or low-pressure readings will trigger immediate stop-engine alarms and can cause the engine to shut down unexpectedly
Where it is. The engine oil pressure sensor is located low on the driver’s side of the engine block near the front. It is mounted directly into the lower section of the cast aluminum oil filter module assembly, positioned just beneath the water pump housing. In this two-sensor cluster, it is the rearmost sensor. Access requires reaching under the module framework, where you will look for a heavy-duty, thumb-sized sensor featuring a hex-shaped brass base and a square, 3-pin black or grey plastic electrical connector head.
Getting at it. Replacement is a relatively easy 15-to-20-minute driveway job, though it can be somewhat tight and messy. On most applications, you will need to unbolt and remove the lower plastic fuel/oil module splash shield to get access to the sensor from beneath the frame rail. You will need a 27mm (or 1-1/16″) deep socket or a dedicated oil pressure switch socket, along with a long extension and ratchet. There is no need to drain the engine oil, but keep a shop rag handy to catch the small amount of oil that will spill from the port when the sensor is unscrewed.
Codes: SPN 100 with FMI 3 or 4 points to an electrical circuit failure, while FMI 1 or 18 indicates a critically low oil pressure condition.
Fitting it. The sensor threads directly into a cast aluminum oil module housing, which makes the threads highly vulnerable to over-tightening. Never use an impact gun or over-torque the new part, as it is very easy to strip the soft aluminum threads out of the expensive module casting. Tighten it firmly by hand using a standard ratchet. Apply a small drop of an oil-resistant liquid thread sealant (such as Loctite 567) to the new brass sensor threads to prevent oil leaks, but ensure you keep the sensor’s opening completely clean and free of sealant and engine grime.
How it typically fails. The typical failure mode for this sensor is an internal diaphragm rupture. Over hundreds of thousands of miles, the constant high-pressure pulsing of the oil causes the internal seal to crack, allowing pressurized engine oil to push straight through the plastic sensor body and fill the electrical connector plug cavity. This oil wicking shorts out the electrical pins, sending erratic voltage signals back to the MCM that cause false low-oil-pressure dashboard alarms.
10 and 11. Coolant Temperature Sensors
Monitors coolant temperature as it re-enters the engine block from the radiator. The MCM uses this data to adjust fueling maps, regulate cooling fan cycles, and drive the dashboard gauge. Sensor faults typically cause hard starting or poor fuel economy.
Which one do you want? There are two coolant temperature sensors on this engine, and they are two separate, individually replaceable parts: the inlet sensor (number 10 in the list above), covered first, and the outlet sensor at the front of the engine on the EGR cooler (number 11), covered after it. Check which one your fault code is pointing at before you start.
Where it is. The inlet coolant temperature sensor is located on the driver’s side of the block at the front, with easy access behind the main cast-iron coolant return pipe, about halfway down the engine toward the oil pan. On some applications, remove the charge air cooler (CAC) intake pipe to gain access from above. Look for a short, brass-bodied sensor with a grey or black 2-pin connector, roughly the size of a thumb.
Getting at it. Replacement is an easy 15-minute driveway job requiring a 19mm deep socket or 6-point box wrench. Drain about a gallon of coolant to prevent coolant spills.
Codes: SPN 110 with FMI 3 or 4 indicates a circuit failure.
Fitting it. Galvanic corrosion can cause the brass threads to seize in the block so use a 6-point socket or 6-point box wrench to prevent rounding off the brass hex. First, apply a penetrating fluid to the threads to prevent the sensor snapping off in the block before attempting to remove the old sensor. Apply PTFE tape to the new sensor threads to prevent coolant leaks.
How it typically fails. Due to extreme and constant heat cycling, the sensor’s internal seals often fail, causing coolant to weep past internal seals and wick up into the connector. Check the connector pins for green corrosion before buying a new part.
Now the outlet sensor (number 11). Everything above is the inlet sensor. The outlet sensor is a different part in a different place, and this is it.
Monitors the temperature of the coolant as it leaves the engine before it passes through the EGR cooler on its way back to the radiator. The MCM relies on this data to monitor EGR cooler thermal efficiency, regulate cooling fan engagement during heavy thermal loading, infer the efficiency of the engine cooling system, and execute protective engine derate protocols if coolant temperatures exceed safe operating limits. Sensor faults typically trigger warning lights, premature cooling fan engagement, or engine derates under load.
Where it is. The coolant outlet temperature sensor is located on the driver’s side at the upper front section of the engine, mounted directly into the EGR cooler housing. Look for a brass-bodied sensor with a black or grey 2-pin connector and an accompanying pigtail harness, positioned right near the EGR crossover piping.
Getting at it. Replacement is an easy 15-to-20-minute driveway job requiring a 19mm deep socket or 6-point wrench. Because the sensor sits in the active cooling loop, drain roughly one to two gallons of coolant from the radiator before removal to keep the work area clean and prevent fluid spills over lower engine components.
Codes: SPN 110 with FMI 0 or 15 indicates high coolant outlet temperatures or a thermal threshold that exceeds a maximum allowable limit, while FMI 3 or 4 indicates an open circuit or short-circuit to ground.
Fitting it. Thermal cycling and galvanic action between the brass threads and the cooler housing can cause seizing; apply a high-quality penetrating oil or lubricant prior to removing the old sensor and always use a 6-point tool to avoid rounding off the brass hex head. Clean the housing threads before installing the new component, and apply a small amount of thread sealant or PTFE tape strictly to the male threads, ensuring no sealant contaminates the sensing probe itself.
How it typically fails. Constant exposure to extreme exhaust heat around the EGR cooler causes the sensor’s internal potting material to break down over extended periods, allowing coolant to migrate into the electrical cavity and short the thermistor. Inspect the mating connector pigtail for moisture, oil, or green corrosion, and replace the pigtail harness if any terminal pin degradation is present.
13. Intake Manifold Pressure (Boost) Sensor
Monitors the air pressure inside the intake manifold after the air has been compressed by the asymmetrical turbocharger and cooled by the charge air cooler. The MCM uses this data to calculate real-time air mass, and determine correct fuel injection timing. Sensor faults typically trigger low power, excessive black smoke, or poor turbo responsiveness.
Where it is. The intake manifold pressure sensor is located on the driver’s side of the engine, mounted directly into the top outer channel of the composite plastic intake manifold. It sits near the front quadrant of the intake tract assembly, completely exposed and clearly visible above the fuel module and main air pipe framework. Look for a small, flat black plastic component with a triangular two-bolt mounting flange and a right-angled, 4-pin electrical connector plug.
Getting at it. Replacement is an easy 5-minute driveway job requiring only a T20 or T25 Torx driver bit. No surrounding engine components, brackets, or plumbing lines need to be removed to gain access, making it immediately serviceable from the top deck.
Codes: SPN 102 with FMI 3 or 4 points to a voltage circuit error, while FMI 16 indicates a severe over boost condition.
Fitting it. The mounting screws thread directly into a composite plastic manifold housing. Never use a standard ratchet or impact gun to install the screws, as it is very easy to strip the soft plastic threads out of the manifold assembly, requiring a thread insert kit or a new intake section; hand-tighten the hold-down screws firmly using a simple screwdriver handle instead. The sensor body installs dry, but you must apply a tiny smear of clean engine oil to its rubber O-ring seal to prevent tearing it upon insertion.
How it typically fails. Due to its physical location directly in the mixed air stream where fresh boost air meets hot, recirculated exhaust gas from the EGR mixer tube, this sensor is subjected to an aggressive environment. It typically fails when a thick layer of carbon soot and wet, vaporized blow-by oil cakes over the inner pressure sensing port, completely blocking the internal diaphragm or insulation-biasing the reading.
Exhaust Manifold Pressure Sensor (no separate part)
Calculates the total exhaust gas backpressure. The MCM relies on this value to command the EGR valve position and balance the exact pressure differential between the intake and exhaust tracts for low emissions. Sensor faults typically trigger EGR correlation codes, illuminated check engine lights, or a forced engine power derate.
Why there is nothing to unbolt. On the Detroit DD13 engine, this is not a discrete, standalone sensor. There is no physical sensor body or threaded part bolted anywhere onto the exhaust manifold layout, which is why it is not numbered or indicated on the example engine photos. Instead, the MCM derives the figure from the sensors it does have. Detroit’s own MCM sensor list for the DD13, DD15 and DD16 carries no exhaust manifold pressure sensor and no exhaust back pressure sensor of any kind, and the physical part behind a code of this sort is the EGR Delta P (differential pressure) sensor, which reads across the venturi pipe in the EGR circuit. Because this is a completely virtual, calculated value, it cannot be physically accessed, unbolted, or replaced in a driveway or shop.
Codes: SPN 411 or SPN 2659 with various FMI indicators signal an exhaust backpressure or EGR flow correlation error. SPN 2659 is Detroit’s EGR flow target error — FMI 1 is low flow — and SPN 411 is the EGR differential pressure circuit. Neither points at a part on the exhaust manifold.
Working near it. When addressing codes related to this system, never attempt to drill or modify the exhaust manifold casting. If threads on the adjacent physical feed EGR tubes are serviced, always apply a high-temperature copper anti-seize compound to prevent the metal line fittings from galling.
How it typically fails. Nine times out of ten, a fault code pointing to an exhaust manifold pressure error is caused by a failure of the physical EGR Delta P sensor, or because its ports — and the ports in the EGR venturi pipe it reads across — are choked shut with a hard, crusty layer of carbon soot and acidic condensation moisture. Detroit’s own procedure for these codes is to pull that sensor and inspect and clean both sets of ports before condemning anything, so do that first.
Barometric Pressure Sensor (no separate part)
Measures the ambient atmospheric pressure as a means to determine the vehicle’s altitude above sea level. The MCM reads this baseline value constantly to calculate air density, allowing it to control turbocharger boost limits, fueling rates, and EGR flow to prevent excessive black smoke or turbocharger over-speeding conditions at high elevations. Sensor faults typically trigger illuminated check engine lights, altitude plausibility errors, or a forced engine derate.
Why there is nothing to unbolt. On the Detroit DD13 engine, this is not a discrete, standalone sensor. There is no physical sensor body, wire harness, or threaded part bolted anywhere onto the exterior layout of the engine, which is why it does not have its own individual number on the example engine photos. Instead, it is an internal electronic component permanently integrated and soldered onto the main circuit board inside the Motor Control Module (MCM) casing—the large silver computer box bolted directly onto the driver’s side of the engine block.
Getting at it. Because this is an internal, non-discrete component, it cannot be physically accessed, unbolted, or cleaned individually in a driveway or shop. Replacing this sensor requires unbolting and swapping the entire multi-thousand-dollar MCM computer block using standard metric sockets, which takes about 30 minutes but requires a factory diagnostic link to program the new module to the truck.
Codes: SPN 108 with FMI 3 or 4 indicates an internal atmospheric pressure circuit defect inside the computer itself.
Working near it. Since the sensor is permanently sealed inside the computer, there are no metal or plastic threads to strip or seize on the block. However, when working near the main engine computer, never attempt to drill, open, or puncture the metal MCM casing to “vent” it or clear a code, as you will permanently destroy the engine’s primary computer module.
How it typically fails. Failure is almost always caused by internal electronic component degradation on the computer’s motherboard or moisture intrusion past the main rubber MCM casing seals over hundreds of thousands of miles. If you suspect an altitude reading error, always check the main computer harness plugs for pinned corrosion before assuming the internal barometric sensor chip itself has failed.
Engine Found in These Trucks (starting 2008-current):
- Freightliner
- Sterling
- Western Star
- Various motor homes / motor coaches
Donde trae el sensor de presión delta del EGR el motor dd15 es modelo 2022 pero no lo trae en el mismo lugar que los modelos anteriores
Where is engine RPM sensor located on cascadia 2016. Not speed sensor but Engine RPM sensor
Their should be a tachometer built into your T.A.C motor. More commonly referred to as the throttle body. It is wired from your tach motor and inputted to your transmission via wiring. Is your vehicle called a cascadia? Acadia?