I have a 2003 Liberty Sport V6 4x4 with 80,000 miles. The Check Engine Light came on with a P1491 code, and no other codes are showing. The fuse is fine, the battery is charged, the alternator is working, and the radiator fan turns on when the AC is on. I replaced the radiator fan relay and cleared the code with my OBD scan tool, but the Check Engine Light still comes on after driving about half a mile, and the P1491 code reappears. I’ve searched online but can’t find a solution. Any advice would be greatly appreciated.
Test the Radiator Fan and check it is working properly. You can do this by turning on the air conditioner and checking to see if the fan works. If not, the fan may need to be replaced, or the Temperature Sensor may be broken, causing this problem. Test the sensor and replace it if needed.
Howdy pals listen, P1491 usually indicates an issue with the radiator fan control relay circuit. This component controls the speed of the radiator fan, which is critical for keeping the engine cool.
Code P1491 usually points to a problem with the secondary air injection (SAI) system, which helps reduce emissions by injecting air into the exhaust stream.
Here are some possible causes and steps to troubleshoot:
- Secondary Air Injection Pump:
- Check Operation: Ensure the SAI pump is functioning and listen for a buzzing sound when it’s active.
- Inspect for Leaks: Look for leaks or damage in the pump and its hoses.
- Replace if Needed: Replace the pump if it’s faulty.
- SAI Solenoid Valve:
- Test Functionality: Verify that the solenoid valve is working correctly.
- Replace if Faulty: Replace the valve if it’s not functioning.
- SAI System Wiring:
- Inspect Wiring: Check for any damaged or loose connections in the wiring.
- Repair or Replace: Fix or replace any damaged wiring.
- Exhaust System:
- Check for Restrictions: Ensure there are no blockages or restrictions in the exhaust system.
- Inspect Catalytic Converter: A clogged or damaged catalytic converter can impact the SAI system.
If replacing the radiator fan relay and clearing the code didn’t resolve the issue, the problem likely lies within the SAI system. Consulting a mechanic specializing in emissions-related issues is advisable.
I have a 2004 WRX rally car, and about a month ago, we fried our ECU during a stage. There were no error lights before that, but after replacing the stock ECU with another stock one, a check engine light came on. I didn’t think much of it at first, assuming it was just reacting to the lack of a stock exhaust, possibly detecting false back pressure. After about three days of daily driving (around 30 km a day to and from work, since my other car isn’t running at the moment), I decided to check the code. I plugged in the Cobb, scanned it, and it showed a P1491 code. Should I be concerned, or should I just reset the ECU? If I do reset it, could there be any issues?
To fix the Jeep code P1491, which relates to a problem with the radiator fan relay circuit, you should:
- Check the fuse for the radiator fan relay.
- Inspect the relay itself and replace it if necessary.
- Examine the wiring and connectors for any damage or corrosion.
- If these steps don’t work, it might require a professional diagnosis for further issues in the fan control system.