Re: CEL/P0453/P0327 OBD-II Fault Codes Question |  |  |
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| CEL/P0453/P0327 OBD-II Fault Codes Question kw986s - 7 years ago |
This is my first post...
Last month I got a CEL on my 2002 Boxster S. I ran an OBD-II diagnostic scan and got two fault codes:
- P0453, fuel tank pressure sensor
- P0327, knock sensor 1
Since my battery was almost five years old and needed to be replaced, I removed the battery and tray to access the fuel tank pressure sensor and discovered two of the three wires to it had become frayed and broken (probably due to vibration and chafing from the sharp metal edge above them, which I cut my finger on). The third wire was also frayed, but not yet broken. I spliced new wire on all three damaged wires, wrapped them, replaced the fuel tank pressure sensor for good measure, put electric tape over the sharp edge above the wrapped wires, reinstalled the battery tray, and installed a new battery.
I started up the car and the CEL did NOT come back on. I have driven the car several times for 162 miles since the repair, and the CEL has NOT come on however, when I run an OBD-II scan the P-0327 fault still comes up. I have cleared the P-0327 fault a couple of times and it returns without the CEL ever coming on.
Do I need to be concerned about the P-0327 fault and have it checked, even though the car appears to be running normally and does NOT display a CEL? Removing the serpentine belt and alternator to get to the knock sensor may be more than I am willing to take on myself.
Thanks in advance for any feedback/recommendations.
Last month I got a CEL on my 2002 Boxster S. I ran an OBD-II diagnostic scan and got two fault codes:
- P0453, fuel tank pressure sensor
- P0327, knock sensor 1
Since my battery was almost five years old and needed to be replaced, I removed the battery and tray to access the fuel tank pressure sensor and discovered two of the three wires to it had become frayed and broken (probably due to vibration and chafing from the sharp metal edge above them, which I cut my finger on). The third wire was also frayed, but not yet broken. I spliced new wire on all three damaged wires, wrapped them, replaced the fuel tank pressure sensor for good measure, put electric tape over the sharp edge above the wrapped wires, reinstalled the battery tray, and installed a new battery.
I started up the car and the CEL did NOT come back on. I have driven the car several times for 162 miles since the repair, and the CEL has NOT come on however, when I run an OBD-II scan the P-0327 fault still comes up. I have cleared the P-0327 fault a couple of times and it returns without the CEL ever coming on.
Do I need to be concerned about the P-0327 fault and have it checked, even though the car appears to be running normally and does NOT display a CEL? Removing the serpentine belt and alternator to get to the knock sensor may be more than I am willing to take on myself.
Thanks in advance for any feedback/recommendations.
| Hmmm. Not entirely sure, but here's my thinking. grant - 7 years ago |
First, good job on finding and fixing the wiring fault. I have not heard of it before - my 17 year old, 228k mile car appears fine.
If you cleared the code, and it comes back, something is tripping the knock sensor fault. I suspect however, that a CEL is only displayed when it has tripped >N times in Y days or miles or years, etc. I'd monitor it (don't clear codes for a while and see what happens).
The serp belt is easy to remove, i cant say for the alternator.
Now, I don't know the details behind the knock sensor code. Is it detecting too many knocks (fuel issue)? Or some parameter that suggests the sensor is failing?
If the latter, i suspect that the only issue would occur if you run lower octane fuel, or have moisture or separation of fuel, or some other issue - e.g.: carbon buildup. Under normal operation with premium fuel i dont believe the base map will generate any significant pre-detonation.
That said, I'd replace it unless its prohibitive.
Grant
Grant
gee-lenahan-at-gee-mail-dot-com
If you cleared the code, and it comes back, something is tripping the knock sensor fault. I suspect however, that a CEL is only displayed when it has tripped >N times in Y days or miles or years, etc. I'd monitor it (don't clear codes for a while and see what happens).
The serp belt is easy to remove, i cant say for the alternator.
Now, I don't know the details behind the knock sensor code. Is it detecting too many knocks (fuel issue)? Or some parameter that suggests the sensor is failing?
If the latter, i suspect that the only issue would occur if you run lower octane fuel, or have moisture or separation of fuel, or some other issue - e.g.: carbon buildup. Under normal operation with premium fuel i dont believe the base map will generate any significant pre-detonation.
That said, I'd replace it unless its prohibitive.
Grant
Grant
gee-lenahan-at-gee-mail-dot-com
| Re: CEL/P0453/P0327 OBD-II Fault Codes Question MarcW - 7 years ago |
Quote
kw986s
This is my first post...
Last month I got a CEL on my 2002 Boxster S. I ran an OBD-II diagnostic scan and got two fault codes:
- P0453, fuel tank pressure sensor
- P0327, knock sensor 1
Since my battery was almost five years old and needed to be replaced, I removed the battery and tray to access the fuel tank pressure sensor and discovered two of the three wires to it had become frayed and broken (probably due to vibration and chafing from the sharp metal edge above them, which I cut my finger on). The third wire was also frayed, but not yet broken. I spliced new wire on all three damaged wires, wrapped them, replaced the fuel tank pressure sensor for good measure, put electric tape over the sharp edge above the wrapped wires, reinstalled the battery tray, and installed a new battery.
I started up the car and the CEL did NOT come back on. I have driven the car several times for 162 miles since the repair, and the CEL has NOT come on however, when I run an OBD-II scan the P-0327 fault still comes up. I have cleared the P-0327 fault a couple of times and it returns without the CEL ever coming on.
Do I need to be concerned about the P-0327 fault and have it checked, even though the car appears to be running normally and does NOT display a CEL? Removing the serpentine belt and alternator to get to the knock sensor may be more than I am willing to take on myself.
Thanks in advance for any feedback/recommendations.
Does the OBD2 scan tool show you the CEL is active? You may have to go to the data view to see this. If the CEL is not active the error is stale and doesn't mean anything.
That covers active.
There is another error classification. Pending.
In the case of pending the CEL will be dark but the code "real" in that the DME is detecting the triggering error condition but just not enough to make the error active (and possibly permanent depending on the error code).
And that brings me to the 3rd and final error class: Permenant. Is the scanner reading "permanent" errors? If so even though the CEL is not on the error will still be present as a permanent error can only be cleared by the DME after so many warm up cycles without detecting the triggering error condtion. The CEL won't be on but the code will be readable.
Might mention with my OBD2 scan tool I have to select which of the 3 types of errors to check for. But other scanners might deliver active and pending and maybe even permanent with just a "read errors" request.
| Re: CEL/P0453/P0327 OBD-II Fault Codes Question kw986s - 7 years ago |
Thanks for the comments. Follow-up:
After seeing a post on the 986 Forum called "Knock Sensor Help" by Miles1, today I removed the front engine cover and used a flashlight to inspect the wires/harness from the knock sensor behind the alternator (see link/image below). Low and behold, I have the same issue - the wire at the connector attached to the knock sensor was frayed/broken. No telling how long this has been going on, since it does not illuminate the CEL. Looks like I will need to have the Knock sensor connector/wires replaced and the part I need is available on Parts Geek...
ADMIN: fixed pic links
Edited 1 time(s). Last edit at 09/11/2016 07:51AM by Boxsterra. (view changes)
After seeing a post on the 986 Forum called "Knock Sensor Help" by Miles1, today I removed the front engine cover and used a flashlight to inspect the wires/harness from the knock sensor behind the alternator (see link/image below). Low and behold, I have the same issue - the wire at the connector attached to the knock sensor was frayed/broken. No telling how long this has been going on, since it does not illuminate the CEL. Looks like I will need to have the Knock sensor connector/wires replaced and the part I need is available on Parts Geek...
ADMIN: fixed pic links
Edited 1 time(s). Last edit at 09/11/2016 07:51AM by Boxsterra. (view changes)
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