1993 Probe GT Check Engine Code 5

1993 ALL OTHER MAKES ALL OTHER MODELS
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MARK SLOCUM
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  • 1 POST
My check engine light comes on with a code of 5. Can not find a source to find out what that code is. The manual has 2,3, then 8. Also the code either doesn't clear with the rest of the codes or it fails simoly by turning the ignition on. I checked this by unplugging the MAF sensor and turn the car on. i recieved a code of 5 and 8 (8 for the MAF sensor). I cleared the code by disconnecting the negative battery and holding down the brake pedal. When turned back on to check to see if it cleared, the 5 was still there and the 8 was gone. I'm stumped. any suggestions?[/code]
Jan 25, 2006 at 4:40 AM
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COSMO
  • ✓Experienced Mechanic
  • 347 POSTS
Hey seeing as that is really a mazda motor in your car, I can answer this one. It is the code for the knock sensor, which is under the intake manifold. Did you replace the rocker cover gaskets recently? The knock sensor harness often gets streched when removing the intake plenum or gets crushed under the intake when re-installing the plenum after replacing the rocker gaskets. Replacing the knock sensor is no easy task or for the faint at heart on a 2.5L DOHC engine. First check and see if it is pluged in. The connector for it is on the throttle body and is grey with one black wire coming in, if you see any damage to this wire...its gonna need to be replaced. YOU cannot repair this wire, it is a sheilded wire.

Cosmo...Mazda tech
Jan 26, 2006 at 1:35 PM
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Suggested Repair

Code 5 indicates the knock sensor under the intake manifold. Check that the grey single-wire connector on the throttle body is plugged in and inspect the shielded black wire for stretch or crush damage, often caused by intake plenum or rocker cover work. If the wire is damaged it cannot be repaired and the knock sensor/harness must be replaced; replacement on the 2.5L DOHC is difficult.

Conversation Summary

The owner of a 1993 Probe GT has a persistent OBD1 code 5 that remains after battery disconnect and appears even with the ignition on, while a test MAF code cleared normally. The expert identified code 5 as the knock sensor, located under the intake manifold, and advised checking the grey connector on the throttle body and the shielded wire, which is often damaged during plenum or rocker gasket work and cannot be repaired.

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