1999 Boxster CEL
10-18-2017, 03:25 AM
#1
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1999 Boxster CEL
Hello,
Just bought a 99' Boxster at 70k. Car is in a good shape and runs great. Bought it from San Fransisco, and drove it to LA. On my way to LA, CEL came on, and checked the codes today at AutoZone (P1125, P1123, P1128, P0455).
P1125: oxygen sensor adaptation, upper load range, Bank 1, above limit.
P1123: O2S Sensing Range 1 Cyl. 1-3
P1128: O2S Range 2 Cyl. 1-3
For these codes, I know I think I need to replace the O2 sensors. First I'll clean the MAF sensor, and will reset the battery and see if CEL comes on again with the same codes. If it does again, I will replace the 02 sensors, but I don't know which one to replace. Range 1? Range 2? Which ones should I replace? Front, rear?
P0455 Fuel Tank Ventilation System (Major Leak)
For this code I have no idea what to do. Maybe it is gas cap related which I replaced with an aftermarket one 2 days ago as the original one had cracks in the seal.
Any ideas would be appriciated..
thanks,
Ali
Just bought a 99' Boxster at 70k. Car is in a good shape and runs great. Bought it from San Fransisco, and drove it to LA. On my way to LA, CEL came on, and checked the codes today at AutoZone (P1125, P1123, P1128, P0455).
P1125: oxygen sensor adaptation, upper load range, Bank 1, above limit.
P1123: O2S Sensing Range 1 Cyl. 1-3
P1128: O2S Range 2 Cyl. 1-3
For these codes, I know I think I need to replace the O2 sensors. First I'll clean the MAF sensor, and will reset the battery and see if CEL comes on again with the same codes. If it does again, I will replace the 02 sensors, but I don't know which one to replace. Range 1? Range 2? Which ones should I replace? Front, rear?
P0455 Fuel Tank Ventilation System (Major Leak)
For this code I have no idea what to do. Maybe it is gas cap related which I replaced with an aftermarket one 2 days ago as the original one had cracks in the seal.
Any ideas would be appriciated..
thanks,
Ali
10-18-2017, 11:49 AM
#2
Race Director
Hello,
Just bought a 99' Boxster at 70k. Car is in a good shape and runs great. Bought it from San Fransisco, and drove it to LA. On my way to LA, CEL came on, and checked the codes today at AutoZone (P1125, P1123, P1128, P0455).
P1125: oxygen sensor adaptation, upper load range, Bank 1, above limit.
P1123: O2S Sensing Range 1 Cyl. 1-3
P1128: O2S Range 2 Cyl. 1-3
For these codes, I know I think I need to replace the O2 sensors. First I'll clean the MAF sensor, and will reset the battery and see if CEL comes on again with the same codes. If it does again, I will replace the 02 sensors, but I don't know which one to replace. Range 1? Range 2? Which ones should I replace? Front, rear?
P0455 Fuel Tank Ventilation System (Major Leak)
For this code I have no idea what to do. Maybe it is gas cap related which I replaced with an aftermarket one 2 days ago as the original one had cracks in the seal.
Any ideas would be appriciated..
thanks,
Ali
Just bought a 99' Boxster at 70k. Car is in a good shape and runs great. Bought it from San Fransisco, and drove it to LA. On my way to LA, CEL came on, and checked the codes today at AutoZone (P1125, P1123, P1128, P0455).
P1125: oxygen sensor adaptation, upper load range, Bank 1, above limit.
P1123: O2S Sensing Range 1 Cyl. 1-3
P1128: O2S Range 2 Cyl. 1-3
For these codes, I know I think I need to replace the O2 sensors. First I'll clean the MAF sensor, and will reset the battery and see if CEL comes on again with the same codes. If it does again, I will replace the 02 sensors, but I don't know which one to replace. Range 1? Range 2? Which ones should I replace? Front, rear?
P0455 Fuel Tank Ventilation System (Major Leak)
For this code I have no idea what to do. Maybe it is gas cap related which I replaced with an aftermarket one 2 days ago as the original one had cracks in the seal.
Any ideas would be appriciated..
thanks,
Ali
P1125: Oxygen sensing adaptation range 1 (cylinders 4-6) lean limit. Fuel/air mixture so rich that the control is up to the lean limit. Possible cause: Fuel pressure too high; fuel injector leaking.
P1123: Same as P1125 except cylinders 1-3 affected.
In both errors above: Oxygen sensing active; time since engine start up between 250 and 350 seconds; engine temperature above 144F; intake air temperature below 194F; air mass flow above 29kg/h; engine speed above 880 rpm.
Test steps are to check fuel pressure. Remove fuel pressure test cap from fuel injection rail. Connect fuel pressure gauge using Baum tool 378 adn Porsche adapter 9559 to test port. Actvate fuel pump. There's a paragraph on removing the fuel pump relay and bridging terminals 30 and 87 (id'd as 3 and 5 on relay panel) with a fused shop-made test harness. I think in this case instead of doing the bridge thing the tech just disconnects the fuel pump from the vehicle wiring harness and when he's ready to test pressure connects 12V shop power to the fuel pump.
Anyhow, with the engine off fuel pressure should be 55psi +/- 3psi. With engine running 48psi +/- 3psi.
Note! The test port seal is not reusable, the cap must be replaced after removal.
P1128: Oxygen sensing adaptation range 2 (cylinders 1-3) enrichment limit. Fuel/air mixture is so lean that the control is up to the enrichment limit. Possible causes: air intake leak; fuel pressure too low; fuel injectors contaminated; fuel supply volume too low.
P1128 is the "flip side" of P1123.
What can happen -- I observed this a couple of times with my Boxster -- is there is a problem, in the case of my Boxster it proved to be a leaking oil tube filler cap, but I didn't know that at the time.
After a while -- towards the end of my 30 mile commute to work or from work to home the CEL would come on. Most of the time the error; P1128 (or the other error for the other bank) pointed to too much air and the DME had reached its adaptation (enrichment) limit. But once in a while the error pointed to too much fuel and the DME had reached its lean limit.
What would happen is the cap would leak and the DME would adapt adding fuel to compensate for the unmetered air getting past the cap. But then occasionally the cap would stop leaking and the DME would have to undo the adaptation and remove fuel. And it would go too far before the senosrs indicated the air/fuel mixture was acceptable and the DME would trigger the P1123.
The see-sawing between a too lean condition and a too rich condition -- though most of the time the error pointed to a too lean condition -- had me (mis)diagnose the problem as bad MAF. After I replaced the MAF and the error codes returned -- though they stayed away a time just long enough for me to relax -- with the help of a co-worker (with better hearing) found the oil filler tube cap leaking. At low engine speeds the leak was severe. However, at higher engine speeds the amount of air that could get past the cap was insignificant compared to the total volume of air the engine was consuming.
A new cap fixed the problem. The original cap lasted around 150K miles. And about 150K miles later the replacement cap was showing signs of leaking and I had to replace the cap again.
P0455: Tank pressure sensor -- above limit. Possible causes: Tank cap loose or missing; vent lines disconnected from EVAP canister; vent lines disconnected from tank; vent lines disconnected from purge valve; vent lines disconnected from EVAP purge valve; break in vent lnes.
Gee I think maybe the vent lines need looking at...
Seriously, check fuel tank cap. My 2002 Boxster cap lasted just around 300K miles. The tether broke. I got a new cap. I checked the old cap and I'm surprised it was not leaking. The sealing ring had small cracks all the way around. But other owners have found the tank cap can leak at fewer miles.
Next check the vent lines at the EVAP canister. Check the lines are connected and the lines are not cracked/broken (or possibly damaged by mice).
Check the vent lines at the purge valve.
Check the vent lines at the tank. Remove battery. Remove lower battery box cover. Check if vent lines are connected to the fuel tank sending unit. Check the lines are not cracked or broken or have mice damage.
Check the vent line at the EVAP canister purge valve.
Check the rest of the vent lines for cracking or damage.
Off hand I'd say find/fix the P0455 error and the P11XX errors will go away.
'course, you'll have to address the P0455 error and then clear the codes -- best pick up an OBD2 code reader/data viewer tool so you can easily read the codes/erase them and check engine telemetry in real time -- then road test the car.
If the P11XX errors come back well that's another thread.
Added: I spotted the mention of using an aftermarket fuel cap. This then triggers the "last thing touched first thing suspected" rule and the replacement cap, an aftermarket cap, has to be suspect.
11-20-2020, 09:38 AM
#3
Here's what I have on these codes;
P1125: Oxygen sensing adaptation range 1 (cylinders 4-6) lean limit. Fuel/air mixture so rich that the control is up to the lean limit. Possible cause: Fuel pressure too high; fuel injector leaking.
P1123: Same as P1125 except cylinders 1-3 affected.
In both errors above: Oxygen sensing active; time since engine start up between 250 and 350 seconds; engine temperature above 144F; intake air temperature below 194F; air mass flow above 29kg/h; engine speed above 880 rpm.
Test steps are to check fuel pressure. Remove fuel pressure test cap from fuel injection rail. Connect fuel pressure gauge using Baum tool 378 adn Porsche adapter 9559 to test port. Actvate fuel pump. There's a paragraph on removing the fuel pump relay and bridging terminals 30 and 87 (id'd as 3 and 5 on relay panel) with a fused shop-made test harness. I think in this case instead of doing the bridge thing the tech just disconnects the fuel pump from the vehicle wiring harness and when he's ready to test pressure connects 12V shop power to the fuel pump.
Anyhow, with the engine off fuel pressure should be 55psi +/- 3psi. With engine running 48psi +/- 3psi.
Note! The test port seal is not reusable, the cap must be replaced after removal.
P1128: Oxygen sensing adaptation range 2 (cylinders 1-3) enrichment limit. Fuel/air mixture is so lean that the control is up to the enrichment limit. Possible causes: air intake leak; fuel pressure too low; fuel injectors contaminated; fuel supply volume too low.
P1128 is the "flip side" of P1123.
What can happen -- I observed this a couple of times with my Boxster -- is there is a problem, in the case of my Boxster it proved to be a leaking oil tube filler cap, but I didn't know that at the time.
After a while -- towards the end of my 30 mile commute to work or from work to home the CEL would come on. Most of the time the error; P1128 (or the other error for the other bank) pointed to too much air and the DME had reached its adaptation (enrichment) limit. But once in a while the error pointed to too much fuel and the DME had reached its lean limit.
What would happen is the cap would leak and the DME would adapt adding fuel to compensate for the unmetered air getting past the cap. But then occasionally the cap would stop leaking and the DME would have to undo the adaptation and remove fuel. And it would go too far before the senosrs indicated the air/fuel mixture was acceptable and the DME would trigger the P1123.
The see-sawing between a too lean condition and a too rich condition -- though most of the time the error pointed to a too lean condition -- had me (mis)diagnose the problem as bad MAF. After I replaced the MAF and the error codes returned -- though they stayed away a time just long enough for me to relax -- with the help of a co-worker (with better hearing) found the oil filler tube cap leaking. At low engine speeds the leak was severe. However, at higher engine speeds the amount of air that could get past the cap was insignificant compared to the total volume of air the engine was consuming.
A new cap fixed the problem. The original cap lasted around 150K miles. And about 150K miles later the replacement cap was showing signs of leaking and I had to replace the cap again.
P0455: Tank pressure sensor -- above limit. Possible causes: Tank cap loose or missing; vent lines disconnected from EVAP canister; vent lines disconnected from tank; vent lines disconnected from purge valve; vent lines disconnected from EVAP purge valve; break in vent lnes.
Gee I think maybe the vent lines need looking at...
Seriously, check fuel tank cap. My 2002 Boxster cap lasted just around 300K miles. The tether broke. I got a new cap. I checked the old cap and I'm surprised it was not leaking. The sealing ring had small cracks all the way around. But other owners have found the tank cap can leak at fewer miles.
Next check the vent lines at the EVAP canister. Check the lines are connected and the lines are not cracked/broken (or possibly damaged by mice).
Check the vent lines at the purge valve.
Check the vent lines at the tank. Remove battery. Remove lower battery box cover. Check if vent lines are connected to the fuel tank sending unit. Check the lines are not cracked or broken or have mice damage.
Check the vent line at the EVAP canister purge valve.
Check the rest of the vent lines for cracking or damage.
Off hand I'd say find/fix the P0455 error and the P11XX errors will go away.
'course, you'll have to address the P0455 error and then clear the codes -- best pick up an OBD2 code reader/data viewer tool so you can easily read the codes/erase them and check engine telemetry in real time -- then road test the car.
If the P11XX errors come back well that's another thread.
Added: I spotted the mention of using an aftermarket fuel cap. This then triggers the "last thing touched first thing suspected" rule and the replacement cap, an aftermarket cap, has to be suspect.
P1125: Oxygen sensing adaptation range 1 (cylinders 4-6) lean limit. Fuel/air mixture so rich that the control is up to the lean limit. Possible cause: Fuel pressure too high; fuel injector leaking.
P1123: Same as P1125 except cylinders 1-3 affected.
In both errors above: Oxygen sensing active; time since engine start up between 250 and 350 seconds; engine temperature above 144F; intake air temperature below 194F; air mass flow above 29kg/h; engine speed above 880 rpm.
Test steps are to check fuel pressure. Remove fuel pressure test cap from fuel injection rail. Connect fuel pressure gauge using Baum tool 378 adn Porsche adapter 9559 to test port. Actvate fuel pump. There's a paragraph on removing the fuel pump relay and bridging terminals 30 and 87 (id'd as 3 and 5 on relay panel) with a fused shop-made test harness. I think in this case instead of doing the bridge thing the tech just disconnects the fuel pump from the vehicle wiring harness and when he's ready to test pressure connects 12V shop power to the fuel pump.
Anyhow, with the engine off fuel pressure should be 55psi +/- 3psi. With engine running 48psi +/- 3psi.
Note! The test port seal is not reusable, the cap must be replaced after removal.
P1128: Oxygen sensing adaptation range 2 (cylinders 1-3) enrichment limit. Fuel/air mixture is so lean that the control is up to the enrichment limit. Possible causes: air intake leak; fuel pressure too low; fuel injectors contaminated; fuel supply volume too low.
P1128 is the "flip side" of P1123.
What can happen -- I observed this a couple of times with my Boxster -- is there is a problem, in the case of my Boxster it proved to be a leaking oil tube filler cap, but I didn't know that at the time.
After a while -- towards the end of my 30 mile commute to work or from work to home the CEL would come on. Most of the time the error; P1128 (or the other error for the other bank) pointed to too much air and the DME had reached its adaptation (enrichment) limit. But once in a while the error pointed to too much fuel and the DME had reached its lean limit.
What would happen is the cap would leak and the DME would adapt adding fuel to compensate for the unmetered air getting past the cap. But then occasionally the cap would stop leaking and the DME would have to undo the adaptation and remove fuel. And it would go too far before the senosrs indicated the air/fuel mixture was acceptable and the DME would trigger the P1123.
The see-sawing between a too lean condition and a too rich condition -- though most of the time the error pointed to a too lean condition -- had me (mis)diagnose the problem as bad MAF. After I replaced the MAF and the error codes returned -- though they stayed away a time just long enough for me to relax -- with the help of a co-worker (with better hearing) found the oil filler tube cap leaking. At low engine speeds the leak was severe. However, at higher engine speeds the amount of air that could get past the cap was insignificant compared to the total volume of air the engine was consuming.
A new cap fixed the problem. The original cap lasted around 150K miles. And about 150K miles later the replacement cap was showing signs of leaking and I had to replace the cap again.
P0455: Tank pressure sensor -- above limit. Possible causes: Tank cap loose or missing; vent lines disconnected from EVAP canister; vent lines disconnected from tank; vent lines disconnected from purge valve; vent lines disconnected from EVAP purge valve; break in vent lnes.
Gee I think maybe the vent lines need looking at...
Seriously, check fuel tank cap. My 2002 Boxster cap lasted just around 300K miles. The tether broke. I got a new cap. I checked the old cap and I'm surprised it was not leaking. The sealing ring had small cracks all the way around. But other owners have found the tank cap can leak at fewer miles.
Next check the vent lines at the EVAP canister. Check the lines are connected and the lines are not cracked/broken (or possibly damaged by mice).
Check the vent lines at the purge valve.
Check the vent lines at the tank. Remove battery. Remove lower battery box cover. Check if vent lines are connected to the fuel tank sending unit. Check the lines are not cracked or broken or have mice damage.
Check the vent line at the EVAP canister purge valve.
Check the rest of the vent lines for cracking or damage.
Off hand I'd say find/fix the P0455 error and the P11XX errors will go away.
'course, you'll have to address the P0455 error and then clear the codes -- best pick up an OBD2 code reader/data viewer tool so you can easily read the codes/erase them and check engine telemetry in real time -- then road test the car.
If the P11XX errors come back well that's another thread.
Added: I spotted the mention of using an aftermarket fuel cap. This then triggers the "last thing touched first thing suspected" rule and the replacement cap, an aftermarket cap, has to be suspect.
Just wanted to clarify couple things - I have the infamous 1123 and 1125 codes. Cleaned the MAF - codes returned. I know that my oil filler tube is leaking - saw some oil on the top of the engine and tube is messy - I guess it was leaking from the tube onto the engine. Based on your words - it could be the culprit too? I didn't check the fuel pressure yet - waiting for the new fuel filter to arrive first. Wanted to replace it since I'm more than sure that it previous owner(s) never replaced it in 21 years of the vehicle's life , however it has only 58k miles on it.