I have a v70 automatic 2002, approx 100k miles. The gear change between one and two often has a free wheeling followed by a thud as the change occurs. The thud can happen changing up or down. I took the car to an auto clutch specialist who said the problem was not with the clutch, but the ECM (the ECM light had been on for a while). The diagnostics threw up ECM-2210 and ECM-2110. I had both sensors changed (Front and rear) and the error codes cancelled, which caused the light to go out for a few days. During these few days the gear change was much smoother. Then the light came on again and the gear change went back to its old routine. So my query is, is this a mechanical fault? If so, why does clearing the error codes make it stop?

Every garage I try has a different diagnosis. Any advice most welcome.

Thanks.

 

These codes refer to the O2 sensors being read as out of range (book definition below). They are listed as ECM codes since they are related to emissions/engine management. Since you've replaced both, that rules out some of the possible causes. What remains is a) a system voltage issue b) dirty connectors c) other related power/wiring issues (relays, fuses etc) d) fuel pressure issues. The front O2 sensors controls the fuel trim so that would explain the engine running rough/idling poorly, and a poor running engine can impact vacuum and mess up shift points.

The shop could do a few additional diagnostic checks like inspecting wiring harnesses for frays etc, check relays/fuses (or replace) reseat the ECU and clean its contacts, reseat the TCU and clean its contacts, check for proper fuel pressure.

Doesn't really sound like a transmission problem - seems more wiring/electrical. My recent experience was our S40 was shifting oddly, occasionally gettting stuck in a low gear. Cleaned the TCU connections and the problem has yet to reappear.

Did you have the CEL codes read again after they reappeared?


Code:ECM-2110
Definition:Front Heated Oxygen Sensor (HO2S) (Signal Too High Or Too Low)Description:This diagnostic trouble code (DTC) is stored if the engine control module (ECM) registers a short-circuit to ground or supply voltage or an open-circuit in the preheating circuit for the front heated oxygen sensor (HO2S). The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on. NOTE: Fuel trim switched off and front heated oxygen sensor (HO2S) preheating switched off.Cause:

• Signal too low
• Damaged fuse.
• Open-circuit in the power cable
• Short-circuit to ground in the power cable
• Damaged front heated oxygen sensor (HO2S).
• Signal too high
• Short-circuit to supply voltage in the power cable
• Damaged front heated oxygen sensor (HO2S).

 

Many thanks for this reply. I am in a dilemma as I am being told it is a mechanical fault by some garages WHY FLUSH - Gearbox Site and like yourself, some say that it's an electrical fault. Given I don't want to spend a fortune on such an old car, I am uncertain of a reasonable way to progress. Is the transmission flush a good start?

Thanks.

 

well 100K is not really a huge amount of miles for a car that is supposed to have life time fluids. It wouldn't hurt to do a drain/fill and inspect the fluid for debris etc but to me, that's kind of assuming the worst case scenario first. Try this - pull the dipstick on the transmission and wipe on a white paper towel. Is it reddish brown or black and smells burnt? Is the level up to the cold fill line? If not, look around for any signs of leaking - particularly by the hoses to to the cooler. You can do a simple drain fill and run that through filter paper to see if any debris comes out. Again there's some differing school of thought here. Some suggest fresh fluid is always good, others suggest if you already have tranny damage (the burnt smell/debris is likely from the clutch disk pack) leave it alone as the dirt is what's keeping it from slipping... At this point you probably don't have enough info to know if its a mechanical issue or electrical. Start with checking the level and color of the fluid on the dipstick and then go from there.

 

Thanks. Will do.

 

Do keep in mind that when you wipe your dipstick on the white rag it looks redder and cleaner than it actually is.

A sump dump (drain & fill) takes less than 4 quarts of fluid and possibly a replacement gasket.
One "hard part" people mention is fitting an 8" piece of extension hose to a funnel for refilling.

Have you owned this car from new?

 

No, since 2007.

 

Hi Ladidalimey,
I've got some experience of this.

I have the v70 - 2005 model and I had exactly the same problem a couple of years back (I have higher mileage).
The problem that you're describing sounds exactly like the L1 solenoid getting stuck in your gear box - and this is a known design fault.
The solenoid, over time, manages to build up a kind of silt of oil and aluminium dust, this silt causes the solenoid to be 'sticky' so the ECM sends the signal through to the box to change gear, the rest of the car assumes that you've changed gear but the stickiness of the solenoid gives you a delay - the manifestation of this delay is the clunk that you experience.

So how do you solve this?
1. if it's just started happening you might get away with an oil change (low chance of success, short term fix)
2. have the gearbox reconditioned (I did this, it's also just delaying the problem - it comes back - it's a design flaw)
3. pick up a second hand box from the breakers, go for one with lower mileage (again not a proper fix)
4. Go for a later box, I believe the 2007 model of this box has the issue solved - I'm not however certain that it's a straight swap.

I hope that helps,
Paul.