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Discussion Starter · #1 ·
I am getting some fault codes that I don't understand for my 1994 850 turbo. First, some history. Over the last 3 years, about every 2-3 months I got a 1-4-3 (knock sensor) code. Some of the information I read stated that the knock sensor seldom goes bad and that it can be related to vac. leaks. I did find one hose off and then last fall got codes 443, 143, 435 (?, knock sensor, O2 sensor). I replaced the front O2 sensor with a bosch universal that I carefully soldered the leads on and used shrink tape. It wasn't very long before the check engine light came on. I was sure it would be the knock sensor again but it wasn't. I'm now getting codes 436, 435, 212, 153 (?, O2 sensor, O2, ?). I should also mention that when the check engine light comes on, it seems to have very little effect on engine performance. I may drop a mile per gallon on gas mileage but even that may be coincidental.

As you can see some of these fault codes are not even listed in the code table. Should I have replaced the rear O2 sensor as well? Did I make a mistake using the universal Bosch sensor? What are these codes that aren't listed on the table? If I do need to try replacing the O2 sensor, should I try using Sea Foam first. Thanks for any help you can provide.
 

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You have a number of issues going on. You probably have some that are compounding others. The general thought is that universal sensors don't work well with Volvo's and one post had even stated that Bosch said that the front one is not likely to be compatible on most models. The rear one may be.

I would do a process of elimination and purchase the correct sensors and start from there. Right now you can't even elimate that the universal sensors aren't your problem.

I hope this helps.

Thanks
 

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Discussion Starter · #3 ·
Thanks for quick reply. I was guessing I'd get told to go with a quality O2 sensor and harness. I'm having a hard time understanding why on this model that would make any difference but guess I'll have to try it. Any thoughts on the sea foam application? I see some people are saying helps a lot and others saying maybe a little. Could this clear up the periodic knock sensor code?

Also, have you ever seen a fault code list that includes the unknown codes I listed in my post? Thanks again for the help.
 

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Seafoam will not change any damage done to the engine based on mileage or other factors. Some people have reported some benefits, but it will be an engine by engine scenario.

A few other things you might want to take note of:

-Seafoam removes carbon buildup from valves. On older higher mileage engines this may be a bad thing because the carbon buildup helps engine compression.
-Do NOT let your engine suck in the Seafoam. Pour it in slowly yourself. If you let the car suck it in and let it stall itself it may hydrolock.
-change your oil and clean your plugs immediately following the treatment. Also keep an eye on your O2 sensor, as all that crap blowing through the exhaust can foul it.
 

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Volvo Codes

A1 – Transmission

111 No faults found
112 Solenoid S1 short circuit to battery voltage
113 Transmission control module (TCM) fault
114 Program selector open circuit or short circuit to supply
121 Solenoid S1 short circuit to ground or control module fault
122 Solenoid S1 open circuit
123 Solenoid STH short circuit to battery voltage
124 Mode selector faulty or short circuit to ground
131 Solenoid STH open/short circuit or control module fault
132 Transmission control module(TCM) fault
134 Faulty load signal from ignition control module
141 Oil temperature sensor short circuit to ground
142 Oil temperature sensor open circuit
143 Kickdown switch faulty or short to ground
211 Transmission control module (TCM) fault
212 S2 solenoid short circuit to battery
213 Throttle position (TPS) signal too high
221 S2 solenoid short circuit to ground or control module fault
222 S2 solenoid open circuit
223 Throttle position (TPS) sensor signal too low
231 Throttle position (TPS) sensor sporadic
232 Speedometer signal missing
233 Incorrect speedometer signal
235 High Oil temperature
245 Open or short in Torque limiting circuit
311 RPM signal from transmission missing
312 RPM signal from transmission faulty
313 Faulty signal from gear position sensor (PNP)
321 Shift time too long
322 Incorrect gear ratio
323 Lock up slips or is not engaged
331 Short circuit to battery in SL circuit
332 SL solenoid open or control module fault
333 SL solenoid short or control module fault
 

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Volvo Codes

A2 – Fuel System

111 No faults detected
112 Fault in ECM
115 Injector 1
121 MAF sensor signal
123 ECT signal
125 Injector 2
131 RPM sensor signal missing
132 Battery voltage
135 Injector 3
143 Front knock sensor signal
145 Injector 4
153 Rear HO2S signal
154 EGR system leakage
155 Injector 5
212 Front HO2S signal
214 RPM sensor signal sporadic
223 IAC valve opening signal
225 A/C pressure sensor signal
231 Long term fuel trim, part load
232 Long term fuel trim, idling
233 Long term idle air trim
241 EGR system flow malfunction
245 IAC valve closing signal
311 VSS signal
314 CMP sensor signal
315 EVAP system
325 Memory failure
335 Request for MIL lighting from TCM
411 TP sensor signal
413 EGR temp sensor signal
414 Boost pressure regulation
416 Boost pressure reduction from TCM
432 Temperature warning level 1
433 Rear knock sensor signal
435 Front HO2S slow response
436 Rear HO2S compensation
443 Three way cat. Efficiency
444 Acceleration signal
451 Misfire cylinder 1
452 Misfire cylinder 2
453 Misfire cylinder 3
454 Misfire cylinder 4
455 Misfire cylinder 5
513 Temperature warning level 2
514 Engine cooling fan low speed signal
521 Front HO2S Preheating
522 Rear HO2S Preheating
531 Power stage group A
532 Power stage group B
533 Power stage group C
534 Power stage group D
535 TC control valve signal
541 EVAP valve signal
542 Misfire more than one cylinder
543 Misfire at least one cylinder
544 Misfire more than one cylinder, three way cat damage
545 Misfire at least one cylinder, three way cat damage
551 Misfire cylinder 1, three way cat damage
552 Misfire cylinder 2, three way cat damage
553 Misfire cylinder 3, three way cat damage
554 Misfire cylinder 4, three way cat damage
555 Misfire cylinder 5, three way cat damage
 

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Discussion Starter · #7 ·
Thanks again. I've never seen a fault code list as exhaustive as this. I'm going to pass on the sea foam. It just doesn't seem like it's worth the risk since the engine seems to be running well. I see that all 4 of the recent codes relate to the O2 sensors so I'll order them and see how it goes.
 
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