Troubleshooting Jaguar Check Engine Light

When your Jaguar check engine light turns on it always causes a moment of anxiety. Troubleshooting your Jaguar’s Check Engine Light (CEL) can be initially be done by an owner who is not averse to expending a little elbow grease. The first thing that you or your mechanic should do is read the fault codes with an OBD2 scanner.

Common Causes

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Coomon causes that trigger Jaguar check engine light. 

Spark plugs 

bad spark plugs can cause misfires, which the engine management system will detect. Another cause would be bad spark plug wires, in this cracks or high resistance due to age. In either case, replacement of either the spark plugs or spark plug wires is the solution.

Loose fuel tank cap 

Causes fuel fume leaks that the on board system will detect, causing a lit CEL. There have also been cases where a full tank sets off error codes in the evaporative system, also causing Jaguar check engine light to come on.

Catalytic converter

A broken catalytic converter will cause the CEL to light. Note that catalytic converters are mandated in the U.S. to be warrantied for 8 years or 80,000 miles. If this is indeed the component at fault, then replacement should not cost the owner if it is within the warranty period.

Oxygen sensor

Measures the amount of unburnt fuel in your engine exhaust. A malfunctioning sensor can trigger the CEL. While reasonably sturdy, O2 sensors do fail and you need to replace them as soon as possible. Broken O2 sensors increase fuel consumption noticeably.

Mass airflow sensor

A blocked or faulty airflow sensor will trigger the check engine light. A problem with this sensor will also increase fuel consumption, affect performance, and increase emissions. 

Ignition Coil

Faulty ignition coils will cause a misfire which can cause rough idling and poor engine performance. If left unrepaired for too long, this condition will damage the catalytic converter.

Thermostat

A stuck thermostat will give erroneous temperature readings. The temperature readings may not be within the expected range of the coolant sensor, and a lit CEL will be the result.

Supercharged engine

A leak in the system will cause the CEL to turn on. This will also cause a lean condition which can damage the engine if it is run hard.

EGR system

Exhaust Gas Recirculation (EGR) system can also trigger the CEL. What happens is that one of the seals in the system hardens. This loss of flexibility can cause an air leak which will trigger the CEL.

Jaguar Check Engine Light On / Restricted performance mode

A flashing check engine light denotes a critical fault. As a safety measure, the ECU defaults to limp home mode so that the driver is able to get to a dealer, service shop or other safe place. The engien power is reduced, the engine may shake which is due to the engine misfiring. Continuing to drive the car for long will result in catalytic converter damage and needing possible replacement.

There are many possible causes for a blinking CEL. It can be that a sensor has failed, or an ignition coil is causing a misfire. Problems with the EGR valve, fuel injectors, the engine itself, or rarely, the ECU, can cause a blinking Jaguar check engine light. It can happen when one is just driving along. A blinking CEL has also been reported to occur after an engine wash or when the spark plug wells become flooded with oil.

The only way to determine what is at fault when you have a blinking CEL is to read the codes thrown by the ECU.

What to do when Jaguar CEL turns on

  1. Check gas cap - this is a common cause for a CEL turning on. Sensors will detect a gas fume leak, resulting in a lit CEL. The fix for this is ensuring that the gas cap is fully seated (at least 3 clicks of the cap when tightening). Note that it will take several ignition cycles before the CEL will turn off.
  2. Check engine oil level - an unseated dipstick or low oil level can trigger Jaguar CEL.
  3. Coolant temp - coolant temperature will be indicated by the temperature gauge. In this case, the CEL will have lit because the sensor reads the coolant as too hot or too cold. This is usually caused by a stuck thermostat. It is worthy to note that some of the newer Jaguars use Ford-derived engines, and it may be possible to find a more reliable thermostat from a Ford.
  4. Monitor performance - if you notice that your Jaguar is performing sluggishly, then you may have a clogged catalytic converter. Of course, a bad ignition coil or another fault may be causing the engine to run in safe or limp home mode. Only by reading the codes will you get a better idea of what is causing poor engine performance.
  5. Read the OBD codes - since the OBD (on-board diagnostics) port is standard in all modern cars, investing in an OBD2 scanner is highly recommended. You can buy a dedicated reader that plugs directly into the OBD port. Or you can buy Bluetooth-enabled transmitters that will interface with your smartphone or tablet, where you can display the error codes.

Hod to read Jaguar check engine codes

  1. Locate the diagnostic port under the dashbaord. 
  2. Connect your OBD-II scanner
  3. Turn on the ignition. 
  4. Turn on your OBD2 scanner
  5. Select check OBD-II from the main menu then scroll down to Read Codes. 
  6. Select Read Codes and write down all the codes that come up. 
  7. Research each code, what it means and what are the possible casues. 

Now that you have an idea of some of the things that can trigger your Jaguar’s check engine light, it’s a matter of referencing this article for some of the things you can check. Having an OBD2 scanner is invaluable for pulling the error codes from your car’s ECU. They are cheap and easy to use. If you have another car or two aside from your Jaguar, then the investment is split over several vehicles.

It must also be reiterated that a blinking check engine light on your Jaguar denotes a critical fault. Try to get to a service area within 5 miles and have your car checked. In case the CEL is just lit and not blinking, you should still have the error codes read as soon as possible.