1999 Mazda MX5 Check engine light: Code P1135, P0421.

1999 MAZDA MX5
55,000 MILES • 4 CYL • 2WD • MANUAL
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POSULLIVAN
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I am working on a 1999 Mazda MX5. The performance is fine. Fuel consumption is normal. It meets all emission requirements.

The check engine light comes on after driving after resetting said light. Sometimes after coming on it will go off again by itself after some time without a reset, sometimes not.

The first time the check engine codes were read codes P0421 (CA warm up catalyst) during very cold weather and P1135 (throttle position sensor).

The lamda O2 sensor system was verified to be working normally with a mean value of 1.000. The throttle sensor output was examined and found to be normal.

After check engine light reset, the light cam back on. The P1135 code was again read.

There appears to be nothing wrong but the check engine light continues to come back on.

Please advise.
Mar 20, 2009 at 12:38 PM
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ATTACK9ONEONE
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If its not lambda and throtle sensor it is IAC motor
give your car about 4rpm while standing next to the engine and listen !
Jan 16, 2010 at 9:10 PM