Challenger Engine Sensors & Valves Overview

The oxygen, or O2 sensor, is located in the downpipe of the exhaust system - one sensor before the catalytic converter and one sensor post-catalytic converter. The job of the O2 sensor is to monitor the oxygen content still present in the exhaust after combustion. Monitoring this density allows the ECU to adjust the fuel requirements to keep the air-to-fuel ratio within an allowable limit (the ideal ratio is 14:1). An improper mixture can hurt economy, performance, emissions and if significantly too lean, engine damage as well. 

The way the sensor works is as such. When at operating temperature (around 350 C), the exterior element of the sensor is capable of conducting oxygen ions. When oxygen is still present in the exhaust stream, the ions are deposited onto an interior electrode which produces a voltage. The voltage varies depending on how many ions are deposited, which in turn the ECU is calibrated to interpret and adjust the fuel ratio based on the signal voltage.

If the O2 sensor in your Dodge Challenger goes bad, it could cause a host of symptoms including bad fuel consumption, poor or erratic idling, hard starting, and poor acceleration. It will also cause the check engine light to illuminate. 

Oxygen sensors are a fairly durable item given their location and duty (subjected to road grime and many heat cycles) with a general life capacity of 100,000 miles

The oil pressure switch or oil pressure sensor for a Dodge Challenger with a V8 engine is located on the block, on the passenger side close to the alternator. V6 Challengers will have to remove their upper intake manifold to get access to the sensor. Anyway, the main job of the oil pressure sensor is to monitor the oil pressure and alert if it is critically low or high. In most cases, a check engine light or low oil pressure light is triggered if the engine is running low on oil.

The switch itself is very basic and is comprised of two parts. Inside of the brass housing is a mechanical diaphragm that pushes up depending on the pressure going through the port. On the other side of the diaphragm (the diaphragm serves as a seal) is a flexible silicone circuit. As the diaphragm pushes on the circuit, the electrical resistance in the circuit changes. The ECU reads these resistance values and can calculate the oil pressure based on the resistance value. These sensors can fail over time as the diaphragm breaks or the wires at the top of the sender corrode out.

Dodge, up until 2014, had a major issue with faulty oil pressure switches and such each engine is covered by a service bulletin (SB-10056046-2193) that mandates the faulty sensor be replaced with a new and improved version.

The crankshaft position sensor is the primary sensor that monitors the ignition and fuel injection system in the Dodge Challenger. It works in tandem with the camshaft position sensor to determine the exact position of the crankshaft. The ECU reads the input from both sensors to accurately discern the top dead center point of the first cylinder.

Both sensors will also cause the same symptoms such as hard starting, stalling, or a no start condition. The faulty sensors will also trigger a check engine light. Again, these sensors can fail due to heat cycles and corrosion. 

The crankshaft position sensor can be seen in the right-rear side of the engine block (near the starter) whereas the camshaft position sensor is located on the timing cover in the Dodge Challenger. 

Both sensors work on the principle of detecting a change in magnetic field. The sensors are calibrated to produce a magnetic field and is distorted by the spinning of the crank and the camshaft. The distortions are measured and the ECU can calculate the position of the crank and camshaft based on this signal received.

Located at the side of the throttle body, the TPS or throttle position sensor is engineered to monitor and report the position of the throttle valve or throttle blade. The TPS works on a similar principle as the crankshaft position sensor. Typically, the throttle blade spindle shaft will have a small magnetic area to it. When the blade changes position, it disrupts the magnetic field which is picked up by the throttle position sensor. This disruption is fed to the ECU and throttle position is correlated.

With that being said, a faulty TPS will produce a host of symptoms including sudden idle surging, hesitation while accelerating, sudden engine stalling, and possible issues with shifting (automatic transmission).

The idle air control valve or IAC sensor is located in the throttle body. It has the job of regulating the amount of air flowing inside the engine during idling. The idle air control valve will basically keep the engine running even when the throttle is fully closed, such as when flooring the gas pedal then suddenly applying the brakes. In this scenario, the IAC sensor prevents the engine from stalling even if the throttle is closed by allowing a small amount of airflow to bypass the throttle blade and continue to the intake manifold. 

The main symptoms of a bad or failing idle air control valve are irregular idling speed, erratic idling, engine stalling, and a check engine light on the dash.

The MAP or manifold absolute pressure sensor is utilized to monitor the air mass flow rate in the motor, which is a critical value that dictates overall performance and fuel efficiency. It works similarly to the oil pressure sender. It has a vacuum tube and a sealed housing. The sealed housing has a flexible silicone chip at the bottom and is filled with air at a known pressure. The vacuum tube is subject to the vacuum within the engine. As the vacuum level changes, the flexible silicone chip (fed a constant voltage) presses up or down. As the chip flexes with the vacuum, the voltage changes and is read by the ECU. The ECU then calculates the air based on the voltage signal and uses this value to help determine fuel trim needs.

The error codes P1296/P1297/P0107 are usually associated with a bad MAP and MAF sensor. The usual symptoms of a bad MAP/MAF sensor are excessive fuel consumption, failed emissions tests, and poor acceleration.

The coolant temperature sensor is utilized to monitor the temperature of the coolant or anti-freeze in the motor. This allows the engine ECU to keep the engine running at the optimum temperature and will adjust the fuel injection, ignition timing, the blower fan speed, and air/fuel ratio based on the sensor reading. 

Wondering why the idling speed is higher when the engine is cold, and suddenly returns to normal when the engine gets hotter? The coolant temperature sensor is responsible for this. An electric probe, fed a regulated voltage, is exposed to the coolant. As the coolant passes over the probe, the resistance of the probe will change based on the temperature of the coolant passing over it. As is always the case, the ECU reads the resistance changes and can calculate what the coolant temperature is. When the coolant has reached sufficient temperature, the engine is deemed to have warmed up and the fuel and timing needs will be adjusted accordingly. 

The coolant temperature sensor in the Dodge Challenger can be found in the upper portion of the water pump housing.

The PCV or positive crankcase valve is used to keep the crankcase pressure under control. With each combustion cycle, some of the combustion gas will inevitably push past the piston rings and enter the crankcase. This is called blow by. The job of the PCV is to ventilate the crankcase and prevent excessive pressure from building up. Excessive crankcase pressure can cause seals to leak, in addition to mixing and condensing with the oil and forming sludge or hard oil deposits. In the case of the Challenger, the PCV ventilates the crankcase pressure back into the intake manifold.

The symptoms of a bad PCV valve are aplenty. This includes misfiring at idle, a constantly lean air/fuel mixture, burning oil, hard starting, engine oil leaks, and black smoke from the exhaust. In the presence of a check engine light, the trouble code for a bad PCV valve is P1480.

The EGR or exhaust gas recirculation valve is engineered to help control combustion pollution and reduce peak combustion temperatures. The former is actually a direct result of a latter. An EGR circulates some of the spent exhaust gases back to the cylinder. Inert at this stage, the exhaust gas effectively dilutes the intake charge and lowers the peak combustion temperature. Under high combustion temperatures, the nitrogen inside the chamber can react with oxygen, producing nitrogen oxide. Vented into the atmosphere, nitrogen oxide will then form into nitrogen dioxide, which is a major air pollutant. By lowering the combustion temperature with inert exhaust gas, the nitrogen is unable to react with the oxygen and form nitrogen oxide. 

The symptoms of a faulty EGR valve are rough idling, poor fuel economy, engine hesitation or stalling when accelerating, and knocking or pinging sounds in the motor. EGR valves do fail (usually due to getting gummed up with carbon deposits), however they do not have a specific or intended lifespan.